securemsm-kernel: Fix multiple listener registration on same fd

Currently, multiple listeners can register on same fd which
could lead to potential vulnerabilities of use after free
while unregistering the listener. Add check to prevent more
than one listener registration on a fd.

Change-Id: Ia2973853943b5619bcf2047629b9c193f6a8c5cf
Signed-off-by: Pawan Rai <quic_pawarai@quicinc.com>
Signed-off-by: Ravi Kumar Bokka <quic_c_rbokka@quicinc.com>