This fixes a crash observed when non-existant enable_ms function is
called for jsm driver.
Signed-off-by: NScott Kilau <Scott.Kilau@digi.com>
Signed-off-by: NPaul Larson <pl@linux.vnet.ibm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>