[MIPS] Avoid using LA macro in inline assembly
[MIPS] Avoid using LA macro in inline assembly

LLVM's integrated assembler currently does not expand LA macro correctly
for PIC mode.
This change is replacing LA macro with appropriate instructions.

BUG=130022
TEST=Build Chromium with Clang and integrated as
TEST=Run sandbox_linux_unittests and components_browsertests

Review-Url: https://codereview.chromium.org/1908253003
Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#391527}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk