target/mips: Fix big endian host behavior for interleave MSA instructions

Fix big endian host behavior for interleave MSA instructions. Previous
fix used TARGET_WORDS_BIGENDIAN instead of HOST_WORDS_BIGENDIAN, which
was a mistake.

Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Aleksandar Rikalo <arikalo@wavecomp.com>
Message-Id: <1561543629-20327-9-git-send-email-aleksandar.markovic@rt-rk.com>