MIPS: Remove frame pointer from StackHandler.

MIPS: Remove frame pointer from StackHandler.

Port 36e69a916f2a88664887d2b62f0eaf8400edb182

Original commit message:
This reduces the size of the StackHandler by yet another word. We no
longer need to keep track of the frame pointer, as the stack walk will
be able to recalculate it.

BUG=

Committed: https://crrev.com/0c12ff2db45b9d4d5b789c0f83af45b1c1096c6e
Cr-Commit-Position: refs/heads/master@{#27123}

[paul.l..., 2015-03-10 20:01:45]

paul.lind@imgtec.com changed reviewers:
+ akos.palfi@imgtec.com, balazs.kilvady@imgtec.com, danno@chromium.org,
mstarzinger@chromium.org

[paul.l..., 2015-03-10 20:01:46]

ptal

[Michael Starzinger, 2015-03-10 20:05:40]

LGTM.

[akos.palfi.imgtec, 2015-03-10 20:08:22]

lgtm

[paul.l..., 2015-03-10 20:08:59]

The CQ bit was checked by paul.lind@imgtec.com

[commit-bot: I haz the power, 2015-03-10 20:09:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/997663002/1

[commit-bot: I haz the power, 2015-03-10 20:43:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-10 20:44:05]

Patchset 1 (id:??) landed as
https://crrev.com/0c12ff2db45b9d4d5b789c0f83af45b1c1096c6e
Cr-Commit-Position: refs/heads/master@{#27123}