ARM: omap1: add Kconfig dependencies for unused boards

ARM: omap1: add Kconfig dependencies for unused boards

Legacy board files with no known users are planned to get removed in
early 2023, and this covers the majority of the omap1 boards as well.

According to Tony, the actual users are all on OSK, Nokia770, and
AMS-Delta. Additionally, the sx1 and palmte boards are supported by qemu,
which is convenient for testing, so all five stay around past the initial
board removal.

As omap1 is now part of the multiplatform build and uses the common-clk
framework, it has become easier to convert these to use devicetree
based booting in the future.

Cc: Janusz Krzysztofik <jmkrzyszt@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: linux-omap@vger.kernel.org
Acked-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>