riscv: implement Ssqosid extension and sqoscfg CSR

Implement the sqoscfg CSR defined by the Ssqosid ISA extension
(Supervisor-mode Quality of Service ID). The CSR contains two fields:

  - Resource Control ID (RCID) used determine resource allocation
  - Monitoring Counter ID (MCID) used to track resource usage

The CSR is defined for S-mode but accessing it when V=1 shall cause a
virtual instruction exception. Implement this behavior by calling the
hmode predicate.

Link: https://github.com/riscv-non-isa/riscv-cbqri/blob/main/riscv-cbqri.pdf


Signed-off-by: Kornel Dulęba <mindal@semihalf.com>
[dfustini: rebase on v8.0.50, reword commit message]
Signed-off-by: Drew Fustini <dfustini@baylibre.com>