[GAS][AArch64] Add support for Cortex-A78 and Cortex-A78AE

[Nick Clifton]

Hi Przemyslaw,

> 2020-09-30  Przemyslaw Wirkus  <przemyslaw.wirkus@arm.com>
> 
> 	* config/tc-aarch64.c: Add Cortex-A78 and Cortex-A78AE cores.
> 	* doc/c-aarch64.texi: Update docs.
> 	* NEWS: Update news.

Approved and applied.

Cheers
  Nick