Revert "serial: 8250_mtk: Make sure to select the right FEATURE_SEL"

Revert "serial: 8250_mtk: Make sure to select the right FEATURE_SEL"

commit f0136f65285bcfb7e8f90d1013723076a35acd51 upstream.

It was found that some MediaTek SoCs are incompatible with this
change. Also, this register was mistakenly understood as it was
related to the 16550A register layout selection but, at least
on some IPs, if not all, it's related to something else unknown.

This reverts commit 6f81fdded0d024c7d4084d434764f30bca1cd6b1.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Fixes: 6f81fdded0d0 ("serial: 8250_mtk: Make sure to select the right FEATURE_SEL")
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Link: https://lore.kernel.org/r/20220510122620.150342-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>