hwrng: ks-sa - Add dependency on IOMEM and OF

This patch adds a dependency for KEYSTONE on HAS_IOMEM and OF to
prevent COMPILE_TEST build failures.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/Kconfig

@@ -495,6 +495,7 @@ config HW_RANDOM_NPCM
 
 config HW_RANDOM_KEYSTONE
 	depends on ARCH_KEYSTONE || COMPILE_TEST
+	depends on HAS_IOMEM && OF
 	default HW_RANDOM
 	tristate "TI Keystone NETCP SA Hardware random number generator"
 	help