MIPS: asm: cmpxchg: Update ISA constraints for MIPS R6 support
MIPS: asm: cmpxchg: Update ISA constraints for MIPS R6 support

MIPS R6 changed the opcodes for LL/SC instructions so we need to set
the correct ISA.

Cc: Matthew Fortune <36abb7af599a47bad00c7d344bf309af35eee58c@imgtec.com>
Signed-off-by: Markos Chandras <5cdbcb0e11d2b5ebc39222958c54a1c6329d0c9d@imgtec.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs