tty: serial: samsung: drop earlycon support for unsupported platforms

tty: serial: samsung: drop earlycon support for unsupported platforms

Commit 1ea35b355722 ("ARM: s3c: remove s3c24xx specific hacks") removed
support here for several old platforms, but kept support for earlycon
for those same platforms.

As earlycon support for otherwise unsupported platforms doesn't seem to
be useful, just drop it as well.

Suggested-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: André Draszik <andre.draszik@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20231019100639.4026283-1-andre.draszik@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>