gtp: simplify error handling code in 'gtp_encap_enable()'

'gtp_encap_disable_sock(sk)' handles the case where sk is NULL, so there
is no need to test it before calling the function.

This saves a few line of code.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/gtp.c

@@ -851,7 +851,6 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[])
 
 		sk1u = gtp_encap_enable_socket(fd1, UDP_ENCAP_GTP1U, gtp);
 		if (IS_ERR(sk1u)) {
-			if (sk0)
 			gtp_encap_disable_sock(sk0);
 			return PTR_ERR(sk1u);
 		}
@@ -860,9 +859,7 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[])
 	if (data[IFLA_GTP_ROLE]) {
 		role = nla_get_u32(data[IFLA_GTP_ROLE]);
 		if (role > GTP_ROLE_SGSN) {
-			if (sk0)
 			gtp_encap_disable_sock(sk0);
-			if (sk1u)
 			gtp_encap_disable_sock(sk1u);
 			return -EINVAL;
 		}