[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>

drivers/crypto/Kconfig

@@ -88,10 +88,16 @@ config CRYPTO_DEV_HIFN_795X
 	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

drivers/crypto/hifn_795x.c

@@ -463,7 +463,7 @@ struct hifn_device
 
 	unsigned int		pk_clk_freq;
 
-#if defined(CONFIG_HW_RANDOM) || defined(CONFIG_HW_RANDOM_MODULE)
+#ifdef CRYPTO_DEV_HIFN_795X_RNG
 	unsigned int		rng_wait_time;
 	ktime_t			rngtime;
 	struct hwrng		rng;
@@ -795,7 +795,7 @@ static struct pci2id {
 	}
 };
 
-#if defined(CONFIG_HW_RANDOM) || defined(CONFIG_HW_RANDOM_MODULE)
+#ifdef CRYPTO_DEV_HIFN_795X_RNG
 static int hifn_rng_data_present(struct hwrng *rng, int wait)
 {
 	struct hifn_device *dev = (struct hifn_device *)rng->priv;
@@ -880,7 +880,7 @@ static int hifn_init_pubrng(struct hifn_device *dev)
 	dprintk("Chip %s: RNG engine has been successfully initialised.\n",
 			dev->name);
 
-#if defined(CONFIG_HW_RANDOM) || defined(CONFIG_HW_RANDOM_MODULE)
+#ifdef CRYPTO_DEV_HIFN_795X_RNG
 	/* First value must be discarded */
 	hifn_read_1(dev, HIFN_1_RNG_DATA);
 	dev->rngtime = ktime_get();