For load and store operations, the code generator for MIPS64 used simple
instructions. In this CL, these instructions are substituted with
corresponding macro-instructions.

TEST=mjsunit/asm/poppler/poppler,
     mjsunit/asm/sqlite3/sqlite,
     mjsunit/asm/sqlite3/sqlite-pointer-masking

BUG=

Change-Id: I1a15be880cd32046b9e5eeea49e5c81ebd2f3138
Reviewed-on: https://chromium-review.googlesource.com/608975Reviewed-by: Miran Karić <Miran.Karic@imgtec.com>
Commit-Queue: Miran Karić <Miran.Karic@imgtec.com>
Cr-Commit-Position: refs/heads/master@{#47279}