MIPS: Emulate the new MIPS R6 BNVC, BNEC and BNEZLAC instructions

MIPS R6 uses the <R6 DADDI opcode for the new BNVC, BNEC and
BNEZLAC instructions.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>