st/va: add support for RGBX and BGRX in VPP

st/va: add support for RGBX and BGRX in VPP

Before it was only possible to convert a NV12 surface to
RGBA or BGRA. This patch uses the same post processing
function, "handleVAProcPipelineParameterBufferType", but
add definitions for RGBX and BGRX.

This patch also makes vlVaQuerySurfaceAttributes more generic
to avoid copy and pasting the same lines.

Signed-off-by: Julien Isorce <j.isorce@samsung.com>
Reviewed-by: Christian K<C3><B6>nig <christian.koenig@amd.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>