[Aarch64] Support ARMv8.2 AT instructions

[Marcus Shawcroft]

On 11 December 2015 at 12:58, Matthew Wahab <matthew.wahab@foss.arm.com> wrote:

> This patch fixes these mistakes.
>
> Tested for aarch64-none-linux-gnu with cross-compiled check-binutils and
> check-gas.
>
> opcodes/
> 2015-12-11  Matthew Wahab  <matthew.wahab@arm.com>
>
>         * aarch64-opc.c (aarch64_sys_reg_supported_p): Add mistakenly
>         removed statement.
>         (aarch64_pstatefield_supported_p): Move feature checks for AT
>         registers ..
>         (aarch64_sys_ins_reg_supported_p): .. to here.
>

OK /Marcus