hwrng: cctrng - Add dependency on OF

The cctrng is unusable on non-DT systems so we should depend
on it.

Signed-off-by: Hadar Gat <hadar.gat@arm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/Kconfig

@@ -476,7 +476,7 @@ config HW_RANDOM_KEYSTONE
 
 config HW_RANDOM_CCTRNG
 	tristate "Arm CryptoCell True Random Number Generator support"
-	depends on HAS_IOMEM
+	depends on HAS_IOMEM && OF
 	default HW_RANDOM
 	help
 	  This driver provides support for the True Random Number