portBASE_TYPE is an internal macro defined by the porting layer. This commit
changes all references to BaseType_t which is the official type exposed by
FreeRTOS.
This commit removes the usage of all legacy FreeRTOS data types that
are exposed via configENABLE_BACKWARD_COMPATIBILITY. Legacy types can
still be used by enabling CONFIG_FREERTOS_ENABLE_BACKWARD_COMPATIBILITY.