mm-video: venc: Distinguish between normal NV12 and aligned NV12

Encoder has a hard-requirement of 2K alignment of UV plane.
Apps and other non-camera sources (not aware of this alignment)
will queue YUV420SP buffers, which need an explicit alignment.
But for some other apps(e.g VT) that are aware that the component
wants aligned NV12 and would align it themselves, causing the component
to muck up the buffer by realigning it.

To prevent the confusion, the component now makes a distinction between
NV12 (OMX_COLOR_FormatYUV420SemiPlanar) and aligned NV12 (QOMX_COLOR_\
FORMATYUV420PackedSemiPlanar32).  Clients who prefer to provide aligned
buffers will now set the latter as the input port format.

Change-Id: I73c337660fb825e9b267663266fd4b9d6e35443e