pm3 serial detection on Linux more robust. Fixes #475

Official firmwares < 2018.02 had a different USB Model string (PM3<>proxmark3).
Better to detect based on the vendor string (proxmark.org) which is more stable,
to ease reflashing devices with old firmwares to the RDV4 firmware.
Thanks @fishilico for having pointed it out.

pm3

@@ -21,7 +21,7 @@ PM3LIST=()
 function get_pm3_list_Linux {
     PM3LIST=()
     for DEV in $(find /dev/ttyACM* 2>/dev/null); do
-        if udevadm info -q property -n "$DEV" |grep -q "ID_MODEL=proxmark3"; then
+        if udevadm info -q property -n "$DEV" |grep -q "ID_VENDOR=proxmark.org"; then
             PM3LIST+=("$DEV")
         fi
     done