netifd: ifup-shellscript - fix wrong usage of 'local'

this error was not visible until recent bump to
busybox 1.24.1 stable which introduced a warning message
when keyword 'local' is not used with a shell-function.

this does not change behavior and is a cosmetic cleanup.
fixes the following output:

root@box:~ ifup <interface>
/sbin/ifup: local: line 362: not in a function
/sbin/ifup: local: line 362: not in a function
/sbin/ifup: local: line 1: not in a function

Signed-off-by: Bastian Bittorf <bittorf@bluebottle.com>

SVN-Revision: 47828

package/network/config/netifd/files/sbin/ifup

@@ -67,12 +67,10 @@ if [ -n "$setup_wifi" ] && grep -sq config /etc/config/wireless; then
 		fi
 	}
 
-	local radio_devs
-	local network="$1"
+	network="$1"
 	config_load wireless
 	config_foreach find_related_radios wifi-iface
 
-	local dev
 	for dev in $(echo "$radio_devs" | sort -u); do
 		/sbin/wifi up "$dev"
 	done