staging: mt7621-pci: avoid to re-disable clock for those pcies not in use

Clock driver for this SoC is using some gates to properly enabling
and disabling the access to peripherals. Those gates that are not
in use are properly being automatically disabled by the kernel.
Pcie driver is explicitly doing a 'clk_disable_unprepare' call for
gates of those pcies that are not used. Since kernel has already
disabled them, the following warnings appear:

WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:952 clk_core_disable+0xe4/0x100
pcie2 already disabled
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0 #0
Stack : 81661680 80082d00 807c0000 00000004 00000000
        80a20000 80860000 80792380
        814503d4 80862e83 00000000 1431b70 81454360
        00000000 00000000 80792380
        81431a08 ffffefff fffffea 00000000 81431a14
        0000007b 80868820 ffffffff
        80792380 1431c70 803d7a24 00000009 807f3a74
        00000001 815df810 00000018 0000000 80a20000
...
Call Trace:
[<80007ed8>] show_stack+0x28/0xf0
[<80381e40>] dump_stack_lvl+0x60/0x80
[<8002cf90>] __warn+0xcc/0x140
[<8002d090>] warn_slowpath_fmt+0x8c/0xac
[<803d7a24>] clk_core_disable+0xe4/0x100
[<803da468>] clk_disable+0x38/0x58
[<804cb730>] mt7621_pci_probe+0x980/0xa50
[<8041e624>] platform_probe+0x50/0xbc
[<8041bfe4>] really_probe.part.0+0xa8/0x340
[<8041c3dc>] driver_probe_device+0x4c/0x154
[<8041cb88>] __driver_attach+0xb4/0x1b4
[<80419a38>] bus_for_each_dev+0x68/0xa4
[<8041b1e8>] bus_add_driver+0x134/0x214
[<8041d3bc>] driver_register+0x98/0x154
[<80001648>] do_one_initcall+0x50/0x1a8
[<808ea1fc>] kernel_init_freeable+0x270/0x30c
[<806dd9dc>] kernel_init+0x20/0x110
[<80002d98>] ret_from_kernel_thread+0x14/0x1c

WARNING: CPU: 0 PID: 1 at drivers/clk/clk.c:810 clk_core_unprepare+0xf4/0x194
pcie2 already unprepared
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Tainted: G        W 5.14.0 #0
Stack : 81661680 80082d00 807c0000 00000004 00000000
        00000000 81431bc4 80a20000
        80860000 80792380 814503d4 80862e83 00000000
        00000001 81431b70 81454360
        00000000 00000000 80792380 81431a08 ffffefff
        00000000 ffffffea 00000000
        81431a14 0000009b 80868820 ffffffff 80792380
        00000001 81431c70 803d7764
        00000009 807f3a74 00000001 815df810 00000018
        8040b36c 00000000 80a20000
...
Call Trace:
[<80007ed8>] show_stack+0x28/0xf0
[<80381e40>] dump_stack_lvl+0x60/0x80
[<8002cf90>] __warn+0xcc/0x140
[<8002d090>] warn_slowpath_fmt+0x8c/0xac
[<803d7764>] clk_core_unprepare+0xf4/0x194
[<803d97c4>] clk_unprepare+0x30/0x48
[<804cb738>] mt7621_pci_probe+0x988/0xa50
[<8041e624>] platform_probe+0x50/0xbc
[<8041bfe4>] really_probe.part.0+0xa8/0x340
[<8041c3dc>] driver_probe_device+0x4c/0x154
[<8041cb88>] __driver_attach+0xb4/0x1b4
[<80419a38>] bus_for_each_dev+0x68/0xa4
[<8041b1e8>] bus_add_driver+0x134/0x214
[<8041d3bc>] driver_register+0x98/0x154
[<80001648>] do_one_initcall+0x50/0x1a8
[<808ea1fc>] kernel_init_freeable+0x270/0x30c
[<806dd9dc>] kernel_init+0x20/0x110
[<80002d98>] ret_from_kernel_thread+0x14/0x1c

Avoid to explicitly disable already disabled pcie gates
fixes the problem.

Fixes: cc4e864a ("staging: mt7621-pci: make use of kernel clock apis")
Reported-by: DENG Qingfang <dqfext@gmail.com>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20210727054058.10612-1-sergio.paracuellos@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-pci/pci-mt7621.c

@@ -422,7 +422,6 @@ static void mt7621_pcie_init_ports(struct mt7621_pcie *pcie)
 			dev_err(dev, "pcie%d no card, disable it (RST & CLK)\n",
 				slot);
 			mt7621_control_assert(port);
-			clk_disable_unprepare(port->clk);
 			port->enabled = false;
 
 			if (slot == 0) {