Apparently

 SMMLS r, b, c, a

computes

 r = ((a << 32) - b * c) >> 32

while the documentation is kinda misleading and states that it should
compute

 r = a - ((b * c) >> 32)

The actual behavior is kinda useless, so we drop the instruction again.

TEST=cctest,unittests
TBR=dcarney@chromium.org

Review URL: https://codereview.chromium.org/654653004

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@24577 ce2b1a6d-e550-0410-aec6-3dcde31c8c00