[mips][msa] Change constant used in ori tests to avoid conflict with bseti (also xori to avoid bnegi)

Upcoming commit(s) are going to add support for bseti and bnegi. This would
cause some existing tests to (correctly) change behaviour and emit a different
instruction. This patch prevents this by changing the constant used in ori and
xori tests so that they will not be matchable by the bseti and bnegi patterns
when these instructions are matchable from normal IR.