ACPI: processor_idle: Fix memory leak in acpi_processor_power_exit()

[ Upstream commit e18afcb7b2a12b635ac10081f943fcf84ddacc51 ]

After unregistering the CPU idle device, the memory associated with
it is not freed, leading to a memory leak:

unreferenced object 0xffff896282f6c000 (size 1024):
  comm "swapper/0", pid 1, jiffies 4294893170
  hex dump (first 32 bytes):
    00 00 00 00 0b 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc 8836a742):
    [<ffffffff993495ed>] kmalloc_trace+0x29d/0x340
    [<ffffffff9972f3b3>] acpi_processor_power_init+0xf3/0x1c0
    [<ffffffff9972d263>] __acpi_processor_start+0xd3/0xf0
    [<ffffffff9972d2bc>] acpi_processor_start+0x2c/0x50
    [<ffffffff99805872>] really_probe+0xe2/0x480
    [<ffffffff99805c98>] __driver_probe_device+0x78/0x160
    [<ffffffff99805daf>] driver_probe_device+0x1f/0x90
    [<ffffffff9980601e>] __driver_attach+0xce/0x1c0
    [<ffffffff99803170>] bus_for_each_dev+0x70/0xc0
    [<ffffffff99804822>] bus_add_driver+0x112/0x210
    [<ffffffff99807245>] driver_register+0x55/0x100
    [<ffffffff9aee4acb>] acpi_processor_driver_init+0x3b/0xc0
    [<ffffffff990012d1>] do_one_initcall+0x41/0x300
    [<ffffffff9ae7c4b0>] kernel_init_freeable+0x320/0x470
    [<ffffffff99b231f6>] kernel_init+0x16/0x1b0
    [<ffffffff99042e6d>] ret_from_fork+0x2d/0x50

Fix this by freeing the CPU idle device after unregistering it.

Fixes: 3d339dc ("cpuidle / ACPI : move cpuidle_device field out of the acpi_processor_power structure")
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/acpi/processor_idle.c

@@ -1430,6 +1430,8 @@ int acpi_processor_power_exit(struct acpi_processor *pr)
 		acpi_processor_registered--;
 		if (acpi_processor_registered == 0)
 			cpuidle_unregister_driver(&acpi_idle_driver);
+
+		kfree(dev);
 	}
 
 	pr->flags.power_setup_done = 0;