Codec2: optimize plane copy for formats with depth > 8

Amend the condition to check if a buffer qualifies
for plane-copy by including the bit-depth

Test:
    android.media.cts.ImageReaderDecoderTest#testOtherH265_10BitImage

Bug: 210947256
Change-Id: I95f7b42475c3d893061aafb9eba818ca2f1148b5