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

[LEDE Commits]

blogic pushed a commit to source.git, branch master:
https://git.lede-project.org/6439e396772a67bf058ff76b15cb9a6dec1882cc

commit 6439e396772a67bf058ff76b15cb9a6dec1882cc
Author: Nickolay Ledovskikh <nledovskikh at gmail.com>
AuthorDate: Fri Dec 16 14:14:05 2016 +0300

    uqmi: 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/uqmi/files/lib/netifd/proto/qmi.sh | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/package/network/utils/uqmi/files/lib/netifd/proto/qmi.sh b/package/network/utils/uqmi/files/lib/netifd/proto/qmi.sh
index 05b9242..cab9cb9 100755
--- a/package/network/utils/uqmi/files/lib/netifd/proto/qmi.sh
+++ b/package/network/utils/uqmi/files/lib/netifd/proto/qmi.sh
@@ -42,6 +42,8 @@ proto_qmi_setup() {
 		proto_set_available "$interface" 0
 		return 1
 	}
+
+	device="$(readlink -f $device)"
 	[ -c "$device" ] || {
 		echo "The specified control device does not exist"
 		proto_notify_error "$interface" NO_DEVICE