[Patch, AArch64] Add support for preload instruction hints in PRFM <prfop> operand

[nick clifton]

Hi Yufeng,

> 2013-01-04  Yufeng Zhang <yufeng.zhang@arm.com>
>
>          * aarch64-opc.c (aarch64_prfops): Update to support PLIL1KEEP,
>          PLIL1STRM, PLIL2KEEP, PLIL2STRM, PLIL3KEEP and PLIL3STRM.
>
> gas/testsuite/
>
> 2013-01-04  Yufeng Zhang <yufeng.zhang@arm.com>
>
>          * gas/aarch64/system.d: Update.

Approved and applied.

Cheers
   Nick