Revert "[media] v4l: vb2-memops: use vma slab when vma allocation"

Please revert this patch: vm_area_cachep is not exported, so you cannot use
this in a module.

This reverts commit 5ed1c328ea077d70e1ebcd5188dc77cdc754df3a.

Reported-by: Hans Verkuil <hverkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --cc drivers/media/v4l2-core/videobuf2-memops.c
Simple merge