Adding AndoirdOpaque Colorformat to OMX

Adding an enum to indicate an android opaque OMX
colorformat. This will inform the encoder that
the actual colorformat will be relayed by the
Frames read from the GRAlloc Buffers

Related to bug id: 4529323

Change-Id: Iddc5bd1ce8ca2b2506a57aadf5fc91ff0c7b78ef