[PATCH][GAS][AArch64] Define BRBE system registers

[Nick Clifton]

Hi Przemyslaw,

> OK for master branch?

Approved - please apply.

> gas/ChangeLog:
> 2020-10-08  Przemyslaw Wirkus  <mailto:przemyslaw.wirkus@arm.com>
> 
> 	* NEWS: Docs update.
> 	* testsuite/gas/aarch64/brbe-invalid.d: New test.
> 	* testsuite/gas/aarch64/brbe-invalid.l: New test.
> 	* testsuite/gas/aarch64/brbe-invalid.s: New test.
> 	* testsuite/gas/aarch64/brbe.d: New test.
> 	* testsuite/gas/aarch64/brbe.s: New test.
> 
> opcodes/ChangeLog:
> 2020-10-08  Przemyslaw Wirkus  <mailto:przemyslaw.wirkus@arm.com>
> 
> 	* aarch64-opc.c: Add BRBE system registers.

Cheers
  Nick