arm64: dts: mediatek: mt7988: move uart0 and spi1 pins to soc dtsi

In order to use uart0 or spi1 there is only 1 possible pin definition
so move them to soc dtsi to reuse them in other boards and avoiding
conflict if defined twice.

Suggested-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Link: https://lore.kernel.org/r/20250516180147.10416-7-linux@fw-web.de


Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>