cephfs,mon: rename variable to a better name

cephfs,mon: rename variable to a better name

Signed-off-by: Rishabh Dave <ridave@redhat.com>
(cherry picked from commit cf68e49597dc065d375666d0e4cb237cef223419)

Conflicts:
src/mon/FSCommands.cc
- The region was to be applied in region use "std::vector" to a declare
  a variable but main branch uses "vector" instead. Using either makes
  no difference since because vector has been imported in to the
  namespace.