plugins: add MM_PLUGIN_REQUIRED_QCDM to plugins requiring QCDM

The new QCDM port probing and grabbing mechanism implements a new
property for detecting the plugins which require the QCDM port to
be probed and grabbed.

Add the property to the affected plugins.

plugins/generic/mm-plugin-generic.c

@@ -100,7 +100,7 @@ mm_plugin_create (void)
                       MM_PLUGIN_IS_GENERIC,         TRUE,
                       MM_PLUGIN_ALLOWED_SUBSYSTEMS, subsystems,
                       MM_PLUGIN_ALLOWED_AT,         TRUE,
-                      MM_PLUGIN_ALLOWED_QCDM,       TRUE,
+                      MM_PLUGIN_REQUIRED_QCDM,      TRUE,
                       MM_PLUGIN_ALLOWED_QMI,        TRUE,
                       MM_PLUGIN_ALLOWED_MBIM,       TRUE,
                       NULL));