[source] comgt: add support of using device symlinks.

[LEDE Commits]

blogic pushed a commit to source.git, branch master:
https://git.lede-project.org/13ab314b0b4a8106c8325f5bdf1232b6896f637f

commit 13ab314b0b4a8106c8325f5bdf1232b6896f637f
Author: Nickolay Ledovskikh <nledovskikh at gmail.com>
AuthorDate: Fri Dec 16 14:14:05 2016 +0300

    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 at gmail.com>
---
 package/network/utils/comgt/files/3g.sh       | 2 ++
 package/network/utils/comgt/files/directip.sh | 1 +
 package/network/utils/comgt/files/ncm.sh      | 2 ++
 3 files changed, 5 insertions(+)

diff --git a/package/network/utils/comgt/files/3g.sh b/package/network/utils/comgt/files/3g.sh
index b0cdae2..d438cb7 100644
--- a/package/network/utils/comgt/files/3g.sh
+++ b/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
diff --git a/package/network/utils/comgt/files/directip.sh b/package/network/utils/comgt/files/directip.sh
index 79b8c32..381bfb0 100644
--- a/package/network/utils/comgt/files/directip.sh
+++ b/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
diff --git a/package/network/utils/comgt/files/ncm.sh b/package/network/utils/comgt/files/ncm.sh
index 09c2c18..cf3cef6 100644
--- a/package/network/utils/comgt/files/ncm.sh
+++ b/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