target/loongarch: Add fixed point bit instruction translation

target/loongarch: Add fixed point bit instruction translation

This includes:
- EXT.W.{B/H}
- CL{O/Z}.{W/D}, CT{O/Z}.{W/D}
- BYTEPICK.{W/D}
- REVB.{2H/4H/2W/D}
- REVH.{2W/D}
- BITREV.{4B/8B}, BITREV.{W/D}
- BSTRINS.{W/D}, BSTRPICK.{W/D}
- MASKEQZ, MASKNEZ

Signed-off-by: Song Gao <[email protected]>
Signed-off-by: Xiaojuan Yang <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-Id: <20220606124333.2060567[email protected]>
Signed-off-by: Richard Henderson <[email protected]>