[PATCH][GAS] aarch64: Update LS64 feature with system register

[Przemyslaw Wirkus]

> Hi Przemyslaw,
> 
> > OK for master branch?
> 
> Approved - please apply.

commit 4a3e3e228280ebbd6320743c1bc2f1401e70300c

> Cheers
>    Nick
> 
> > gas/ChangeLog:
> > 2020-11-05  Przemyslaw Wirkus  <mailto:przemyslaw.wirkus@arm.com>
> >
> > 	* testsuite/gas/aarch64/ls64.d: New test.
> > 	* testsuite/gas/aarch64/ls64.s: Test for ACCDATA_EL1 register.
> >
> > opcodes/ChangeLog:
> > 2020-11-05  Przemyslaw Wirkus  <mailto:przemyslaw.wirkus@arm.com>
> >
> > 	* aarch64-opc.c: Add ACCDATA_EL1 system register
>