[mips] Fix predicate for the MipsTruncIntFP pattern

This is a follow-up to the rL337171. This patch fixes regression
introduced by the r337171 and enables MipsTruncIntFP pattern.

Differential revision: https://reviews.llvm.org/D49469

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@337392 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed