AArch64: remove extraneous padding
AArch64: remove extraneous padding

The structs BarrierOp, PrefetchOp, PSBHintOp are in AArch64AsmParser.cpp
(inside anonymous namespace).  This diff changes the order of fields and
removes the excessive padding (8 bytes).

Patch by Alexander Shaposhnikov!

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@279173 91177308-0d34-0410-b5e6-96231b3b80d8

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