arm64: dts: ti: iot2050: Factor out arduino connector bits

A new variant is to be added which will not have a arduino connector
like the existing ones. Factor out all bits that are specific to this
connector.

The split is not perfect because wkup_gpio0 is defined based on what is
common to all variants having the connector, thus containing also
connector-unrelated information. But this is still cleaner than
replicating this node into all 4 variants.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Link: https://lore.kernel.org/r/3366367dc9f190c9e21027b9a810886791e99245.1707463401.git.jan.kiszka@siemens.com
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>