[Mips] Remove unused mips_CPUs_Group options group. It's better to join all MIPS-related options to the new m_mips_Features_Group later.
[Mips] Remove unused mips_CPUs_Group options group. It's better to join
all MIPS-related options to the new m_mips_Features_Group later.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@192291 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang