The direct register access ioctls were defined as kernel internal only,
but they are very useful for debugging hardware from userspace and are
used as such.  Officially export them.

VIDIOC_INT_[SG]_REGISTER is renamed to VIDIOC_DBG_[SG]_REGISTER 
Definition of ioctl and struct v4l2_register is moved from v4l2-common.h 
to videodev2.h.

Types used in struct v4l2_register are changed to the userspace 
exportable versions (u32 -> __u32, etc). 

Use of VIDIOC_DBG_S_REGISTER requires CAP_SYS_ADMIN permission, so move 
the check into the video_ioctl2() dispatcher so it doesn't need to be 
duplicated in each driver's call-back function. CAP_SYS_ADMIN check is 
added to pvrusb2 (which doesn't use video_ioctl2).
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>