ramips: replace backticks by $(...)

This replaces deprecated backticks by more versatile $(...) syntax.

While at it, remove some useless cat commands and deprecated
egrep commands.

Signed-off-by: Adrian Schmutzler <[email protected]>

target/linux/ramips/base-files/etc/board.d/02_network

@@ -14,10 +14,10 @@ ramips_setup_rt3x5x_vlans()
 	local wanports=""
 	local lanports=""
 	for port in 5 4 3 2 1 0; do
-		if [ `swconfig dev rt305x port $port get disable` = "1" ]; then
+		if [ "$(swconfig dev rt305x port $port get disable)" = "1" ]; then
 			continue
 		fi
-		if [ `swconfig dev rt305x port $port get lan` = "0" ]; then
+		if [ "$(swconfig dev rt305x port $port get lan)" = "0" ]; then
 			wanports="$port:wan $wanports"
 		else
 			lanports="$port:lan $lanports"
@@ -503,7 +503,7 @@ ramips_setup_interfaces()
 			"0:lan" "1:lan" "2:lan" "3:lan" "4:wan" "7t@eth0"
 		;;
 	*)
-		RT3X5X=`cat /proc/cpuinfo | egrep "(RT3.5|RT5350)"`
+		RT3X5X=$(grep -E "(RT3.5|RT5350)" /proc/cpuinfo)
 		if [ -n "${RT3X5X}" ]; then
 			ramips_setup_rt3x5x_vlans
 		else

target/linux/ramips/base-files/lib/preinit/07_set_preinit_iface_ramips

@@ -4,7 +4,7 @@
 #
 
 ramips_set_preinit_iface() {
-	RT3X5X=`cat /proc/cpuinfo | egrep "(RT3.5|RT5350|MT7628|MT7688|MT7620|MT7621)"`
+	RT3X5X=$(grep -E "(RT3.5|RT5350|MT7628|MT7688|MT7620|MT7621)" /proc/cpuinfo)
 
 	if [ -n "${RT3X5X}" ]; then
 		# The ethernet switch driver enables VLAN by default, but