[GAS][Arm] PR 25472: Enable DSP instructions with +mve

[Nick Clifton]

Hi Andre,

> gas/ChangeLog:
> 2020-01-28  Andre Vieira  <andre.simoesdiasvieira@arm.com>
> 
>         PR gas/25472
>     * config/tc-arm.c (armv8m_main_ext_table): Refactored +dsp adding.
>         (armv8_1m_main_ext_table): Refactored +dsp adding and enabled dsp for
>     +mve.
>     * testsuite/gas/arm/mve_dsp.d: New test.

Approved for 2.33, 2.34 and mainline.  Please apply.

Cheers
  Nick