crypto: omap-des - add COMPILE_TEST and fix CONFIG_OF=n build

crypto: omap-des - add COMPILE_TEST and fix CONFIG_OF=n build

CRYPTO_DEV_OMAP_DES only depends on ARCH_OMAP2PLUS, which is ARM-only
and selects OF via ARM's USE_OF, making any non-OF code unreachable.

Add COMPILE_TEST so the driver can be built with CONFIG_OF=n, making the
non-OF code reachable.

Fix the resulting non-OF build failures:

- omap_des_irq() was defined inside a CONFIG_OF block, but is referenced
  unconditionally from omap_des_probe(). Move the CONFIG_OF guard so it
  only covers omap_des_get_of().

- The non-OF omap_des_get_of() stub took a struct device *, while
  omap_des_probe() passes a struct platform_device *. Make the stub
  prototype match the OF implementation and the caller.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>