fix syntax error in preinit hook (#6610)

SVN-Revision: 19461

target/linux/atheros/base-files/lib/preinit/15_preinit_iface_atheros

@@ -13,8 +13,9 @@ preinit_ip() {
 			else
 				ifname=eth0
 			fi
-		pi_ifname=$ifname
-	}
+			pi_ifname=$ifname
+		}
+	fi
 	[ -n "$pi_ifname" ] && grep "$pi_ifname" /proc/net/dev >/dev/null && {
 		ifconfig $pi_ifname $pi_ip netmask $pi_netmask broadcast $pi_broadcast up
     	}