Merge pull request ARMmbed#12972 from kivaisan/ALT1250_enable_tac_info_for_reg_status_mbed_5_15

Alt1250 enable tac info for registration status (mbed 5.15)

Author: 0xc0170

features/cellular/framework/targets/Altair/ALT1250/PPP/ALT1250_PPP.cpp

@@ -35,7 +35,7 @@ using namespace events;
 #endif
 
 static const intptr_t cellular_properties[AT_CellularBase::PROPERTY_MAX] = {
-    AT_CellularNetwork::RegistrationModeEnable,// C_EREG
+    AT_CellularNetwork::RegistrationModeLAC,// C_EREG
     AT_CellularNetwork::RegistrationModeDisable,    // C_GREG
     AT_CellularNetwork::RegistrationModeLAC,    // C_REG
     1,  // AT_CGSN_WITH_TYPE