[PATCH][AArch64][gas] Add support for Cortex-A73

[Nick Clifton]

Hi Kyrill,

> 2016-06-03  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
> 
>     * config/tc-aarch64.c (aarch64_cpus): Add cortex-a73 entry.
>     * doc/c-aarch64.texi (-mcpu): Document cortex-a73 value.

Approved - please apply.

Cheers
  Nick