arm: mach-sc5xx: clean up Kconfig

Moves common options between all SC5xx series boards to the ARCH_SC5XX
option instead of duplicating them.

Also, it was possible to select multiple of the SoC support options.
Given a U-Boot binary can only support a single platform, this moves
the SoC selection to a `choice`, making them mutually exclusive.

Signed-off-by: Oliver Gaskell <Oliver.Gaskell@analog.com>
2 files changed