AArch64: The pattern match should check the range of the immediate value.
Or we can generate some illegal instructions.
E.g. shrn2 v0.4s, v1.2d, #35. The legal range should be in [1, 16].


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195941 91177308-0d34-0410-b5e6-96231b3b80d8