net: sysctl_net_core: delete unused variable

Variable "one" is not used anymore it seem and I run into:

	net/core/sysctl_net_core.c:26:12: warning: 'one' defined but not used [-Wunused-variable]
 	 static int one = 1;

Signed-off-by: Amit Pundir <amit.pundir@linaro.org>