comgt: add support of using device symlinks.

It's useful when using multiple usb devices that should be bound to
certain usb ports. Symlinks are created by hotplug handlers.

Signed-off-by: Nickolay Ledovskikh <nledovskikh@gmail.com>

package/network/utils/comgt/files/3g.sh

@@ -31,6 +31,8 @@ proto_3g_setup() {
 	json_get_var dialnumber dialnumber
 
 	[ -n "$dat_device" ] && device=$dat_device
+
+	device="$(readlink -f $device)"
 	[ -e "$device" ] || {
 		proto_set_available "$interface" 0
 		return 1

package/network/utils/comgt/files/directip.sh

@@ -27,6 +27,7 @@ proto_directip_setup() {
 
 	[ -n "$ctl_device" ] && device=$ctl_device
 
+	device="$(readlink -f $device)"
 	[ -e "$device" ] || {
 		proto_notify_error "$interface" NO_DEVICE
 		proto_set_available "$interface" 0

package/network/utils/comgt/files/ncm.sh

@@ -45,6 +45,8 @@ proto_ncm_setup() {
 		proto_set_available "$interface" 0
 		return 1
 	}
+
+	device="$(readlink -f $device)"
 	[ -e "$device" ] || {
 		echo "Control device not valid"
 		proto_set_available "$interface" 0