bearer-qmi: explicitly ignore PCOs with undefined contents:

There is nothing to process in this kind of PCO fields:

  <<<<<< TLV:
  <<<<<<   type       = "Operator Reserved PCO" (0x2f)
  <<<<<<   length     = 8
  <<<<<<   value      = 00:00:00:00:00:00:00:00
  <<<<<<   translated = [ mcc = '0' mnc = '0' mnc_includes_pcs_digit = 'no' app_specific_info = '{}' container_id = '0' ]

Fixes https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/690

src/mm-bearer-qmi.c

@@ -576,6 +576,10 @@ process_operator_reserved_pco (MMBearerQmi                           *self,
             NULL))
         return;
 
+    /* Ignore PCOs with undefined contents */
+    if (!tmp_mcc && !tmp_mcc && !container_id && !array->len)
+        return;
+
     app_specific_info_str = ((array->len > 0) ?
                              mm_utils_bin2hexstr ((guint8*) (array->data), array->len) :
                              NULL);