riscv/pmap.c: Don't pass hartid map to 'smp_rendezvous_cpus'

[bnovkov]

Summary

The pm_active bitmask is indexed by hart IDs which can differ from
CPU IDs. pmap_invalidate_range_svinval assumes that the map is
indexed by CPU IDs, which is wrong and causes remote TLB invalidations
on unrelated CPUs.

Fix this by adding a routine that converts a hart-indexed bitmask
to a CPU ID-indexed bitmask. While we're here, fix a similar issue
in pmap_active_cpus.

Fixes: 99360212c739 ("riscv/pmap.c: Add an Svinval-aware variant of pmap_invalidate_range")
Reported by: markj