ARM: omap1: remove unused board files

All board support that was marked as 'unused' earlier can
now be removed, leaving the five machines that that still
had someone using them in 2022, or that are supported in
qemu.

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