AuthMonitor: no need to check permission in MDS caps

AuthMonitor: no need to check permission in MDS caps

For "fs authorize" command, AuthMonitor.cc checks if permissions is "r"
or begins with "rw". This check is redundant now.
AuthMonitor::valid_caps() runs MDSAuthCaps.parse() which now runs same
check for the MDS caps, regardless of the command.

Signed-off-by: Rishabh Dave <ridave@redhat.com>
(cherry picked from commit 8e1e322054ea14eb5e59969439c0ea27885503ab)

Conflicts:
	qa/tasks/cephfs/test_admin.py
	Since line numbers where the patch should be applied is
	different in quincy branch compared to main branch, the conflict
	occured.