IB/mad: Remove redundant check from smi_check_local_dr_smp()

smi_check_local_dr_smp() is called only from two places in core/mad.c
It returns 0 or 1.  In smi_check_local_dr_smp(), it checks for
a directed route SMP but this function is only called when the SMP
is a directed route so this is a NOP.

Signed-off-by: Hal Rosenstock <halr@voltaire.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>