soc: versatile: enable compile testing

soc: versatile: enable compile testing

Enable compile testing for broader build coverage.  None of the drivers
use anything from "asm", so code should build everywhere.
CONFIG_PLAT_VERSATILE is being selected by driver dependencies
(CONFIG_ARCH_INTEGRATOR and CONFIG_ARCH_REALVIEW), so directory can be
always added to Makefile targets without impacting other configurations.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/20240825-soc-dev-fixes-v1-4-ff4b35abed83@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>