[mips] Remove MipsCC::CCInfo. NFC.

Summary:
It's now passed in as an argument to functions that need it. Eventually
this argument will be replaced by the 'this' pointer for a MipsCCState
object.

Depends on D5966

Reviewers: vmedic

Reviewed By: vmedic

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5967