lib: sbi: Add support for smcntrpmf

This adds the support for ISA extension smcntrpmf. When some inhibit flags
are set by a lower privilege mode for new CSRs added by smcntrpmf, OpenSBI
sets the appropriate values correspondingly.

Signed-off-by: Kaiwen Xue <kaiwenx@andrew.cmu.edu>
Signed-off-by: Kaiwen Xue <kaiwenx@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Atish Patra <atishp@rivosinc.com>