mon/FSCommands: fix variable names and function names in calls

mon/FSCommands: fix variable names and function names in calls

PR #51942 today and PR #52409 was merged last week. Latter PR changed
"fs" to "fsp" and made mds_map and fscid private and introduced
get_mds_map() and get_fsicd() methods instead.

Combination of former and latter PR introduced compilation errors & made
it impossible to build the binaries on the latest main branch. This
commit attemps to fix this issue.

Fixes: https://tracker.ceph.com/issues/62729
Signed-off-by: Rishabh Dave <ridave@redhat.com>