s390/qeth: use DEFINE_MUTEX for qeth_mod_mutex

Consolidate declaration and initialization of a static variable.
While at it reduce its scope in qeth_core_load_discipline(), and simplify
the return logic accordingly.

Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed