crypto: picoxcell - Allow driver to build COMPILE_TEST is enabled

crypto: picoxcell - Allow driver to build COMPILE_TEST is enabled

Driver only has runtime but no build time dependency with ARCH_PICOXCELL.
So it can be built for testing purposes if COMPILE_TEST option is enabled.

This is useful to have more build coverage and make sure that the driver
is not affected by changes that could cause build regressions.

Suggested-by: Arnd Bergmann <[email protected]>
Signed-off-by: Javier Martinez Canillas <[email protected]>
Acked-by: Jamie Iles <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>