[media] v4l: ti-vpe: make sure VPDMA line stride constraints are met

When VPDMA fetches or writes to an image buffer, the line stride must be a
multiple of 16 bytes. If it isn't, VPDMA HW will write/fetch until the next
16 byte boundry. This causes VPE to work incorrectly for source or destination
widths which don't satisfy the above alignment requirement.
In order to prevent this, we now make sure that when we set pix format for the
input and output buffers, the VPE source and destination image line strides are
16 byte aligned. Also, the motion vector buffers for the de-interlacer are
allocated in such a way that it ensures the same alignment.

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>