[CRYPTO] hifn795x: Disallow built-in hifn795x when HW_RANDOM is m

Currently it is possible to select HW_RANDOM as a module and have
hifn795x built-in.  This causes a build problem because hifn795x
will then call hwrng_register which isn't built-in.

This patch introduces a new config option to control the hifn795x
RNG which lets us avoid this problem.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig
index 74bd599..8a70a9e 100644
--- a/drivers/crypto/Kconfig
+++ b/drivers/crypto/Kconfig
@@ -88,10 +88,16 @@
 	select CRYPTO_DES
 	select CRYPTO_ALGAPI
 	select CRYPTO_BLKCIPHER
+	select HW_RANDOM if CRYPTO_DEV_HIFN_795X_RNG
 	depends on PCI
 	help
 	  This option allows you to have support for HIFN 795x crypto adapters.
 
-
+config CRYPTO_DEV_HIFN_795X_RNG
+	bool "HIFN 795x random number generator"
+	depends on CRYPTO_DEV_HIFN_795X
+	help
+	  Select this option if you want to enable the random number generator
+	  on the HIFN 795x crypto adapters.
 
 endif # CRYPTO_HW