selftest/net/ipsec.c: Remove unneeded semicolon

fix semicolon.cocci warning:
tools/testing/selftests/net/ipsec.c:1788:2-3: Unneeded semicolon

Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>