As reported by syzbot below, kfifo_alloc'd memory would not be freed
if a non-zero return value is triggered in wacom_probe. This patch
creates and uses devm_kfifo_alloc to allocate and free itself.

BUG: memory leak
unreferenced object 0xffff88810dc44a00 (size 512):
  comm "kworker/1:2", pid 3674, jiffies 4294943617 (age 14.100s)
  hex dump (first 32 bytes):
   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 00 00 00 00 00  ................
  backtrace:
   [<0000000023e1afac>] kmalloc_array include/linux/slab.h:592 [inline]
   [<0000000023e1afac>] __kfifo_alloc+0xad/0x100 lib/kfifo.c:43
   [<00000000c477f737>] wacom_probe+0x1a1/0x3b0 drivers/hid/wacom_sys.c:2727
   [<00000000b3109aca>] hid_device_probe+0x16b/0x210 drivers/hid/hid-core.c:2281
   [<00000000aff7c640>] really_probe+0x159/0x480 drivers/base/dd.c:554
   [<00000000778d0bc3>] driver_probe_device+0x84/0x100 drivers/base/dd.c:738
   [<000000005108dbb5>] __device_attach_driver+0xee/0x110 drivers/base/dd.c:844
   [<00000000efb7c59e>] bus_for_each_drv+0xb7/0x100 drivers/base/bus.c:431
   [<0000000024ab1590>] __device_attach+0x122/0x250 drivers/base/dd.c:912
   [<000000004c7ac048>] bus_probe_device+0xc6/0xe0 drivers/base/bus.c:491
   [<00000000b93050a3>] device_add+0x5ac/0xc30 drivers/base/core.c:2936
   [<00000000e5b46ea5>] hid_add_device+0x151/0x390 drivers/hid/hid-core.c:2437
   [<00000000c6add147>] usbhid_probe+0x412/0x560 drivers/hid/usbhid/hid-core.c:1407
   [<00000000c33acdb4>] usb_probe_interface+0x177/0x370 drivers/usb/core/driver.c:396
   [<00000000aff7c640>] really_probe+0x159/0x480 drivers/base/dd.c:554
   [<00000000778d0bc3>] driver_probe_device+0x84/0x100 drivers/base/dd.c:738
   [<000000005108dbb5>] __device_attach_driver+0xee/0x110 drivers/base/dd.c:844

https://syzkaller.appspot.com/bug?extid=5b49c9695968d7250a26

Reported-by: syzbot+5b49c9695968d7250a26@syzkaller.appspotmail.com
Signed-off-by: Ping Cheng <ping.cheng@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>