RISC-V: Add basic support for the vector extension

I've started hitting this in CI while testing Andy's vector enablement
series. I'm not entirely sure if there is more to do here, other than
squeezing in the duplicate of what has been done for other extensions.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Luc Van Oostenryck <lucvoo@kernel.org>
1 file changed