Revert "Disable dual stack mode"

This reverts commit 8611474.

Author: Sebastian Stockhammer

features/cellular/framework/targets/GEMALTO/CINTERION/GEMALTO_CINTERION.cpp

@@ -143,7 +143,7 @@ void GEMALTO_CINTERION::init_module_ems31()
         1,  // AT_CGAUTH
         1,  // PROPERTY_IPV4_STACK
         1,  // PROPERTY_IPV6_STACK
-        0,  // PROPERTY_IPV4V6_STACK
+        1,  // PROPERTY_IPV4V6_STACK
     };
     AT_CellularBase::set_cellular_properties(cellular_properties);
     _module = ModuleEMS31;