media: mc-device.c: change media_device_request_alloc to match media_ioctl_info

We modified the type of media_device_request_alloc()'s second
parameter from int* to void* so that it can match the interface
defined in struct media_ioctl_info.

[hverkuil: move #ifdef before variable to avoid compile warning]

Signed-off-by: Frederic Chen <frederic.chen@mediatek.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>