runqemu-if*: Rename confusing variable name

The IFCONFIG variable is really the path to ip and hasn't been
ifconfig for a long time. Rename the variable to something less
confusing.

(From OE-Core rev: eb1c947a056f3e2c80e46e5e606423e85da46caa)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/runqemu-ifdown

@@ -37,14 +37,14 @@ if !ip tuntap del $TAP mode tap 2>/dev/null; then
 	exit 1
 fi
 
-IFCONFIG=`which ip 2> /dev/null`
-if [ "x$IFCONFIG" = "x" ]; then
+IPTOOL=`which ip 2> /dev/null`
+if [ "x$IPTOOL" = "x" ]; then
 	# better than nothing...
-	IFCONFIG=/sbin/ip
+	IPTOOL=/sbin/ip
 fi
-if [ -x "$IFCONFIG" ]; then
-	if `$IFCONFIG link show $TAP > /dev/null 2>&1`; then
-		$IFCONFIG link del $TAP
+if [ -x "$IPTOOL" ]; then
+	if `$IPTOOL link show $TAP > /dev/null 2>&1`; then
+		$IPTOOL link del $TAP
 	fi
 fi
 # cleanup the remaining iptables rules