It is possible that the output region size (e.g. 192x144) is different
from the coded picture size (e.g. 192x256). We may adjust the alignment
parameters so that the padding is respected in GstVideoInfo and use
GstVideoInfo to calculate mfx frame width and height

This fixes the error below when decoding a stream which has different
output region size and coded picture size

0:00:00.057726900 28634 0x55df6c3220a0 ERROR                msdkdec
gstmsdkdec.c:1065:gst_msdkdec_handle_frame:<msdkh265dec0>
DecodeFrameAsync failed (failed to allocate memory)

Sample pipeline:

gst-launch-1.0 filesrc location=output.h265 ! h265parse ! msdkh265dec !
glimagesink