Fix dst crop used in color converter

The dst frame is allocated according to the actual crop size.
When top-left is non-zero, the convert needs to use the dst
rect with top-left adjusted to {0, 0}.

bug: 149667324
test: vendor testing on devices that uses non-zero top-left crop;
CTS MediaMetadataRetrieverTest.
Change-Id: I98ea2e398cf6bb17a6e76116caa145e9be5a110e