arm: neon: return VLC_SUCCESS for packed to planar
All packed cases (UYVY/VYUY/YVYU/YUYV) would eventually fall through to the default case, and thus return VLC_EGENERIC. To fix this, add the missing breaks for each of them.
Caught by Clang's aggressive -Wimplicit-fallthrough, which also warns on fallthrough to the default case.
Edited by Johannes Kauffmann