cdma: allow plugins to override AT+CSS? during registration checking (rh #547294)

Some modems key the AT+CSS? response off their 1X state, so if the
modem has EVDO service but no 1X service, AT+CSS? will provide incorrect
registration state information and the registration checking will
end too early.  Allow modems that can handle more specific registration
checking to skip the AT+CSS? part.

plugins/mm-modem-anydata-cdma.c

@@ -62,6 +62,7 @@ mm_modem_anydata_cdma_new (const char *device,
                                    MM_MODEM_PLUGIN, plugin,
                                    MM_GENERIC_CDMA_EVDO_REV0, evdo_rev0,
                                    MM_GENERIC_CDMA_EVDO_REVA, evdo_revA,
+                                   MM_GENERIC_CDMA_REGISTRATION_TRY_CSS, FALSE,
                                    NULL));
 }