[mips] Add Mips-specific CCIf's for accessing the MipsCCState. NFC.

Reviewers: vmedic

Reviewed By: vmedic

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D6213

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223662 91177308-0d34-0410-b5e6-96231b3b80d8