rpm: fix permissions for /etc/ceph/rbdmap

rpm: fix permissions for /etc/ceph/rbdmap

Prior to this change, the RPM packaging would install /etc/ceph/rbdmap
with exectuable permissions. The execute bit is not necessary and does
not match what the Debian packaging does. Remove the execute bit in this
case.

Fixes: http://tracker.ceph.com/issues/17395
Reported-by: Martin Bukatovic <mbukatov@redhat.com>
Signed-off-by: Ken Dreyer <kdreyer@redhat.com>
(cherry picked from commit d4b84a13960f9f46593bf89dc92bfc3e54b4851e)

Conflicts:
	ceph.spec.in : trivial context resolution