mm-video: vdec: Update output buffer count in thumbnail mode

This change updates the output buffer requirements when thumbnail mode
is enabled. In thumbnail mode the required output buffers equal to 1.
Output Buffer required for thumbnail mode were not updated earlier from
the driver as a result of which allocating memory for default buffer
count failed and thumbnail were not shown for some file formats.

Change-Id: I607a5b0e3bfcad8056ff71557db50d0e268cf348
CRs-Fixed: 513180
mm-video: Fix issue with port reconfiguration specific clip

This change fixes the issue of UI freeze during the
playback of multiple resolution change specific clips
through decoder test app.

CRs-fixed: 476934
Change-Id: Ia5572482073bd743b641319ee246cb483bc1917e
mm-video: vdec: Convey crop information from driver to client

Crop information about uncompressed buffers need to be
conveyed to client to appropriately select the region
to display. This change takes care of this.

Conflicts:

	mm-video/vidc/vdec/src/omx_vdec.cpp

Change-Id: I1ddd129753ad3f6464ea415ded0a61f3b7c9bad6

Conflicts:

	mm-video/vidc/vdec/inc/omx_vdec.h
	mm-video/vidc/vdec/src/omx_vdec.cpp