soc: arm: mps3: Enable FPU, DSP and MVE extensions

This commit updates the MPS3 AN547 SoC configuration to enable the FPU
as well as the DSP and MVE extensions.

Note that the CPU0 of the SSE-300 (and AN547) supports all of the
extensions mentioned above (as for MVE, it supports both MVE-I and
MVE-F).

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>