ceph.spec.in: drop SUSE-specific %py_requires macro

ceph.spec.in: drop SUSE-specific %py_requires macro

%py_requires expands to

BuildRequires: /usr/bin/python
PreReq: python = 2.7

The BuildRequires: is already provided, and the PreReq is wrong because
e.g. SLE11-SP3 (a platform we are trying to support) has Python 2.6.

http://tracker.ceph.com/issues/12351 Fixes: #12351

Signed-off-by: Nathan Cutler <ncutler@suse.com>
(cherry picked from commit cbf6c7b46b42e163950bf7956e5b7565fca961c9)

Conflicts:
	ceph.spec.in
            in master, the %py_requires is in the python-rados package,
            while in firefly it is in the python-ceph package