media: v4l: Add 32-bit packed YUV formats

The formats added in this patch include:
 V4L2_PIX_FMT_AYUV32
 V4L2_PIX_FMT_XYUV32
 V4L2_PIX_FMT_VUYA32
 V4L2_PIX_FMT_VUYX32

These formats enable the trasmission of alpha channel data to other
drivers and userspace applications in addition to YUV data. For
example, buffers generated by drivers in one of these formats
can be used by the Weston compositor to display as a texture or
flipped directly onto the overlay planes with the help of a DRM
driver.

Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>