[AARCH64] Add support of ARMv8.4 in saphira for Qualcomm server part

[Nick Clifton]

Hi Sameera,

> gas/ChangeLog:
> 
> 2018-05-29 Sameera Deshpande <sameera.deshpande@linaro.org>
> 
>         * config/tc-aarch64.c : Add support of ARMv8.4 in saphira.

Approved - please apply.

Cheers
  Nick