HID: hiddev - fix compiler warning

drivers/hid/usbhid/hiddev.c: In function 'hiddev_compat_ioctl':
drivers/hid/usbhid/hiddev.c:746: warning: passing argument 4 of 'hiddev_ioctl' makes
integer from pointer without a cast

Add cast to hiddev_compat_ioctl()

Signed-off-by: Jiri Kosina <jkosina@suse.cz>