[Hexagon] Remove USR_OVF from CtrRegs register class
[Hexagon] Remove USR_OVF from CtrRegs register class

USR_OVF is a subregister of USR, which is a member of CtrRegs. Having both
a register and its proper subregister in the same register class has bad
consequences for lane mask calculation: based solely on the lane mask info,
USR_OVF would not appear to be a subregister of USR.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@282192 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm