libvideoeditor: use vWidth and vHeight for buffer allocation

 - video editor detects crop information from decoder, crop
   width and height will override metadata width and height.
 - decoder is capable of sending crop information where
   crop width and height are smaller than actual resolution.
 - use actual metadata width and height for calculating
   buffer size.

Change-Id: Id1d77c316e3892e6d51a00418052f256629f495f
CRs-Fixed: 452511