[AArch64] Add SVE system registers

[Nick Clifton]

Hi Richard,

> opcodes/
> 	* aarch64-opc.c (aarch64_sys_regs): Add SVE registers.
> 	(aarch64_sys_reg_supported_p): Handle them.
> 
> gas/
> 	* testsuite/gas/aarch64/sve-sysreg.s,
> 	testsuite/gas/aarch64/sve-sysreg.d,
> 	testsuite/gas/aarch64/sve-sysreg-invalid.d,
> 	testsuite/gas/aarch64/sve-sysreg-invalid.l: New tests.

OK for trunk.

Cheers
  Nick