[mips][mips64r6] Correct select patterns that have the condition or true/false values backwards

Summary: This bug caused SingleSource/Regression/C/uint64_to_float and SingleSource/UnitTests/2002-05-02-CastTest3 to fail (among others).

Differential Revision: http://reviews.llvm.org/D4388


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212608 91177308-0d34-0410-b5e6-96231b3b80d8