ipv4: arp: Cleanup in arp.c

Use "IS_ENABLED(CONFIG_FOO)" macro instead of
"defined(CONFIG_FOO) || defined(CONFIG_FOO_MODULE)"

Signed-off-by: Igor Maravic <igorm@etf.rs>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed