target/mips: Amend and cleanup MSA TCG tests

Add missing bits and peaces of the tests of the emulation of certain
MSA (non-immediate variants): some tests were missing two last cases;
some instructions were missing wrappers; some test included wrong
headers; some tests were missing altogether; updated some copywright
preambles; do several other minor cleanups.

Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Signed-off-by: Mateja Marjanovic <mateja.marjanovic@rt-rk.com>
Reviewed-by: Aleksandar Rikalo <arikalo@wavecomp.com>
Message-Id: <1555699081-24577-4-git-send-email-aleksandar.markovic@rt-rk.com>