uqmi: ensure CID is a numeric value before proceeding

The current implementation only checked if uqmi itself executed
correctly which is also the case when the returned value is actually
an error.

Rework this, checking that CID is a numeric value, which can only
be true if uqmi itself also executed correctly.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

package/network/utils/uqmi/files/lib/netifd/proto/qmi.sh

@@ -140,11 +140,11 @@ proto_qmi_setup() {
 
 	[ "$pdptype" = "ip" -o "$pdptype" = "ipv4v6" ] && {
 		cid_4=$(uqmi -s -d "$device" --get-client-id wds)
-		[ $? -ne 0 ] && {
+		if ! [ "$cid_4" -eq "$cid_4" ] 2> /dev/null; then
 			echo "Unable to obtain client ID"
 			proto_notify_error "$interface" NO_CID
 			return 1
-		}
+		fi
 
 		uqmi -s -d "$device" --set-client-id wds,"$cid_4" --set-ip-family ipv4 > /dev/null
 
@@ -177,11 +177,11 @@ proto_qmi_setup() {
 
 	[ "$pdptype" = "ipv6" -o "$pdptype" = "ipv4v6" ] && {
 		cid_6=$(uqmi -s -d "$device" --get-client-id wds)
-		[ $? -ne 0 ] && {
+		if ! [ "$cid_6" -eq "$cid_6" ] 2> /dev/null; then
 			echo "Unable to obtain client ID"
 			proto_notify_error "$interface" NO_CID
 			return 1
-		}
+		fi
 
 		uqmi -s -d "$device" --set-client-id wds,"$cid_6" --set-ip-family ipv6 > /dev/null