V4L/DVB (12906d): V4L : vpif updates for DM6467 vpif capture driver

Following changes done for vpif driver to support vpif capture:-
	1) Current version of display driver defined vpif register
	   space as part for vpif display platform driver resource
	   This is not correct since vpif is common across capture
	   and display drivers. So the resource iomap function is
	   moved to this module
	2) Since there are common registers, a spinlock is added for
	   mutual exclusion.

This has incorporated comments against version v0 of the patch series

Resending to merge to V4L linux-next

Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Muralidharan Karicheri <m-karicheri2@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>