Revert "core: Convert_Scale: Add support for > 8bits."

This reverts commit 8bababd6a7972a3d0e724ac8fb4c3ee8495a7e16.

Sorry I've screewed this one.

This reverts the original change and only adds support for > 8bits.

Signed-off-by: Cyril Hrubis <metan@ucw.cz>