There are cases that USE_SERIALDRIVER is defined but USE_EARLYSERIALINIT not defined in some configs. So use ifdef USE_EARLYSERIALINIT to include up_earlyserialinit anyway.
There are cases that USE_SERIALDRIVER is defined but USE_EARLYSERIALINIT not defined in some configs. So use ifdef USE_EARLYSERIALINIT to include up_earlyserialinit anyway.