[PATCH][GAS][AArch64] Update Cortex-X1 feature flags

[Nick Clifton]

Hi Przemyslaw,

> 2020-10-05  Przemyslaw Wirkus  <przemyslaw.wirkus@arm.com>
> 
> 	* config/tc-aarch64.c: Update Cortex-X1 feature flags.

Approved - please apply.

Cheers
  Nick