hwrng: timeriomem - Breaks an allyesconfig build on s390:

  CC      drivers/char/hw_random/timeriomem-rng.o
drivers/char/hw_random/timeriomem-rng.c: In function 'timeriomem_rng_data_read':
drivers/char/hw_random/timeriomem-rng.c:60: error: implicit declaration of function 'readl'

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/Kconfig

@@ -22,7 +22,7 @@ config HW_RANDOM
 
 config HW_RANDOM_TIMERIOMEM
 	tristate "Timer IOMEM HW Random Number Generator support"
-	depends on HW_RANDOM
+	depends on HW_RANDOM && HAS_IOMEM
 	---help---
 	  This driver provides kernel-side support for a generic Random
 	  Number Generator used by reading a 'dumb' iomem address that