default or selected kernelversion does not have config value CONFIG_SERIAL_LH7A40X_CONSOLE.
Result is shown for kernelversion 5.4.69

Support for console on Sharp LH7A40X serial port

configname: CONFIG_SERIAL_LH7A40X_CONSOLE

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Serial drivers
└─>Support for console on Sharp LH7A40X serial port
In linux kernel since version 2.6.20 (release Date: 2007-02-04)  
Say Y here if you wish to use one of the serial ports as the
system console--the system console is the device which
receives all kernel messages and warnings and which allows
logins in single user mode.

Even if you say Y here, the currently visible framebuffer console
(/dev/tty0) will still be used as the default system console, but
you can alter that using a kernel command line, for example
"console=ttyAM1".