Merge r342946 into the 7.0 branch: [mips] Correct MUL pattern for mips64

[atanasyan]

Bugzilla Link	39613
Resolution	FIXED
Resolved on	Nov 12, 2018 22:07
Version	trunk
OS	All
Blocks	#38454
CC	@tstellar
Fixed by commit(s)	r342946 r346742

Extended Description

Please merge the following revision to the 7.0 branch. This fixes regression introduced in 7.0.

https://reviews.llvm.org/rL342946

[tstellar]

Merged: r346742