[media] media: platform: add VPFE capture driver support for AM437X

This patch adds Video Processing Front End (VPFE) driver for
AM437X family of devices
Driver supports the following:
- V4L2 API using MMAP buffer access based on videobuf2 api
- Asynchronous sensor/decoder sub device registration
- DT support

Signed-off-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
[hans.verkuil@cisco.com: swapped two lines to fix vpfe_release() & add pinctrl include]
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>