MIPS: Fix clang build by removing incorrect inline asm constraint.

Improper use of immediate constraint is slightly non-optimal
with gcc/gnu-as but causes breakage with clang.

This is a cherry-pick of upstream v8 bleeding_edge:
https://chromium.googlesource.com/v8/v8/+/eb68d6fe13f13b0697dd2b4ff00df1d7c997669e

BUG:18789639

Change-Id: I8786262b4bf906aec982b790cbf3982601980cf6
2 files changed