CONFIG_HAVE_STD_PC_SERIAL_PORT is not available for thedefaultarchitecture x86.
Result is shown for architecture mips

CONFIG_HAVE_STD_PC_SERIAL_PORT (not configurable)

modulename: 8250-platform.ko

and/or

configname: CONFIG_HAVE_STD_PC_SERIAL_PORT

Linux/MIPS Kernel Configuration
└─>Machine selection
└─>HAVE_STD_PC_SERIAL_PORT
In linux kernel since version 2.6.12  
is depended by
CONFIG_TOSHIBA_RBTX4938