serial: sc16is7xx: rename Kconfig CONFIG_SERIAL_SC16IS7XX_CORE

serial: sc16is7xx: rename Kconfig CONFIG_SERIAL_SC16IS7XX_CORE

Commit d49216438139
("serial: sc16is7xx: split into core and I2C/SPI parts (core)")
renamed SERIAL_SC16IS7XX_CORE by SERIAL_SC16IS7XX. This means that some
configs should have been updated when I submitted the original patch, but
unfortunately they were not. Geert mentioned for example:
    arch/mips/configs/cu1??0-neo_defconfig

Rename SERIAL_SC16IS7XX to SERIAL_SC16IS7XX_CORE so that existing configs
will still work correctly.

Suggested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Fixes: d49216438139 ("serial: sc16is7xx: split into core and I2C/SPI parts (core)")
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20240603152601.3689319-2-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>