platform/mellanox: mlxreg-hotplug: Add devm_free_irq call to remove flow

Add devm_free_irq() call to mlxreg-hotplug remove() for clean release
of devices irq resource. Fix debugobjects warning triggered by rmmod
It prevents of use-after-free memory, related to
mlxreg_hotplug_work_handler.

Issue has been reported as debugobjects warning triggered by
'rmmod mlxtreg-hotplug' flow, while running kernel with
CONFIG_DEBUG_OBJECTS* options.

[ 2489.623551] ODEBUG: free active (active state 0) object type: work_struct hint: mlxreg_hotplug_work_handler+0x0/0x7f0 [mlxreg_hotplug]
[ 2489.637097] WARNING: CPU: 5 PID: 3924 at lib/debugobjects.c:328 debug_print_object+0xfe/0x180
[ 2489.637165] RIP: 0010:debug_print_object+0xfe/0x180
?
[ 2489.637214] Call Trace:
[ 2489.637225]  __debug_check_no_obj_freed+0x25e/0x320
[ 2489.637231]  kfree+0x82/0x110
[ 2489.637238]  release_nodes+0x33c/0x4e0
[ 2489.637242]  ? devres_remove_group+0x1b0/0x1b0
[ 2489.637247]  device_release_driver_internal+0x146/0x270
[ 2489.637251]  driver_detach+0x73/0xe0
[ 2489.637254]  bus_remove_driver+0xa1/0x170
[ 2489.637261]  __x64_sys_delete_module+0x29e/0x320
[ 2489.637265]  ? __ia32_sys_delete_module+0x320/0x320
[ 2489.637268]  ? blkcg_exit_queue+0x20/0x20
[ 2489.637273]  ? task_work_run+0x7d/0x100
[ 2489.637278]  ? exit_to_usermode_loop+0x5b/0xf0
[ 2489.637281]  do_syscall_64+0x73/0x160
[ 2489.637287]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 2489.637290] RIP: 0033:0x7f95c3596fd7

The difference in release flow with and with no devm_free_irq is listed
below:

bus: 'platform': remove driver mlxreg-hotplug
 mlxreg_hotplug_remove(start)
					-> devm_free_irq (with new code)
 mlxreg_hotplug_remove (end)
 release_nodes (start)
  mlxreg-hotplug: DEVRES REL devm_hwmon_release (8 bytes)
  device: 'hwmon3': device_unregister
  PM: Removing info for No Bus:hwmon3
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (88 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (6 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (5 bytes)
  mlxreg-hotplug: DEVRES REL devm_irq_release (16 bytes) (no new code)
  mlxreg-hotplug: DEVRES REL devm_kzalloc_release (1376 bytes)
   ------------[ cut here ]------------ (no new code):
   ODEBUG: free active (active state 0) object type: work_struct hint: mlxreg_hotplug_work_handler

 release_nodes(end)
driver: 'mlxreg-hotplug': driver_release

Fixes: 1f976f69 ("platform/x86: Move Mellanox platform hotplug driver to platform/mellanox")
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/mellanox/mlxreg-hotplug.c

@@ -694,6 +694,7 @@ static int mlxreg_hotplug_remove(struct platform_device *pdev)
 
 	/* Clean interrupts setup. */
 	mlxreg_hotplug_unset_irq(priv);
+	devm_free_irq(&pdev->dev, priv->irq, priv);
 
 	return 0;
 }