Make ARMAsmPrinter generate the correct alignment specifier syntax in instructions.

The Printer will now print instructions with the correct alignment specifier syntax, like
    vld1.8  {d16}, [r0:64]



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175884 91177308-0d34-0410-b5e6-96231b3b80d8