Camera: Align the CbCr offset to multiple of 16 blocks for
 jpeg encoding.

Align the CbCr offsets to multiple of 16 boundries for
targets using Hardware Jpeg encoder(7x27, 7630). This
padding is needed only for thumbnail buffer.

Allocate a seperate buffer to display postview for 7x27.

Change-Id: I1853dc6e1ea5119b952b3d46254fa07e85e31572