libvideoeditor: use vWidth and vHeight for buffer allocation

Change-Id: I2ab01b8ef79a3ad9b1eb737b2e9f1211a6e668c2
 - 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.
CRs-Fixed: 452511