ipmi_si: fix a memleak in try_smi_init()

Kmemleak reported the following leak info in try_smi_init():

unreferenced object 0xffff00018ecf9400 (size 1024):
  comm "modprobe", pid 2707763, jiffies 4300851415 (age 773.308s)
  backtrace:
    [<000000004ca5b312>] __kmalloc+0x4b8/0x7b0
    [<00000000953b1072>] try_smi_init+0x148/0x5dc [ipmi_si]
    [<000000006460d325>] 0xffff800081b10148
    [<0000000039206ea5>] do_one_initcall+0x64/0x2a4
    [<00000000601399ce>] do_init_module+0x50/0x300
    [<000000003c12ba3c>] load_module+0x7a8/0x9e0
    [<00000000c246fffe>] __se_sys_init_module+0x104/0x180
    [<00000000eea99093>] __arm64_sys_init_module+0x24/0x30
    [<0000000021b1ef87>] el0_svc_common.constprop.0+0x94/0x250
    [<0000000070f4f8b7>] do_el0_svc+0x48/0xe0
    [<000000005a05337f>] el0_svc+0x24/0x3c
    [<000000005eb248d6>] el0_sync_handler+0x160/0x164
    [<0000000030a59039>] el0_sync+0x160/0x180

The problem was that when an error occurred before handlers registration
and after allocating `new_smi->si_sm`, the variable wouldn't be freed in
the error handling afterwards since `shutdown_smi()` hadn't been
registered yet. Fix it by adding a `kfree()` in the error handling path
in `try_smi_init()`.

Cc: stable@vger.kernel.org # 4.19+
Fixes: 7960f18a ("ipmi_si: Convert over to a shutdown handler")
Signed-off-by: Yi Yang <yiyang13@huawei.com>
Co-developed-by: GONG, Ruiqi <gongruiqi@huaweicloud.com>
Signed-off-by: GONG, Ruiqi <gongruiqi@huaweicloud.com>
Message-Id: <20230629123328.2402075-1-gongruiqi@huaweicloud.com>
Signed-off-by: Corey Minyard <minyard@acm.org>

drivers/char/ipmi/ipmi_si_intf.c

@@ -2082,6 +2082,11 @@ static int try_smi_init(struct smi_info *new_smi)
 		new_smi->io.io_cleanup = NULL;
 	}
 
+	if (rv && new_smi->si_sm) {
+		kfree(new_smi->si_sm);
+		new_smi->si_sm = NULL;
+	}
+
 	return rv;
 }