[PATCH] Implement aarch64 neon instruction class SIMD Bitwise Extract - LLVM

[Tim Northover]

> * printNeonUImm8Operand -> printUImmHexOperand
> * printNeonUImm8OperandBare -> printUImm8BareOperand

Sounds great! We'll probably want to look over the whole collection
and rationalise things when we're done, but those are much better than
what we have now.

Cheers.

Tim.