[PATCH][BINUTILS] aarch64: Add support for Check Feature Status Extension.

[Nick Clifton]

Hi Srinath,

> This patch adds support for Check Feature Status Extension (CHK) which
> is mandatory from Armv8.0-A. Also this patch supports "chkfeat" instruction
> (hint #40).
> 
> Regression tested for aarch64-none-elf target and found no regressions.
> 
> Ok for binutils-master?

Approved - please apply.

Cheers
   Nick