Fix the static_assert added in r279536.
Fix the static_assert added in r279536.

The assertion doesn't always hold true as sizeof(SDNodeBits) isn't equal
to sizeof(uint16_t) for some targets. For example, sizeof(SDNodeBits)
evaluates to 1, not 2, for ARM's APCS targets.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@279797 91177308-0d34-0410-b5e6-96231b3b80d8

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