[PATCH][GAS][ARM] Fix AArch32 build attributes for Armv8.4-A.

[Nick Clifton]

Hi Tamar,

> Ok for master?

Approved - please apply.

> And also requesting permission to backport to binutils 2.30.

Also approved - also please apply.

> gas/
> 2018-02-15  Tamar Christina  <tamar.christina@arm.com>
> 
> 	* config/tc-arm.c (cpu_arch_ver): Renumber ARM_ARCH_V8_4A.
> 	* testsuite/gas/arm/attr-march-armv8_4-a.d: New.

Cheers
  Nick