hwrng: st - support compile-testing

Allow compile-testing the st-rng driver if we're not running on an ST
chipset.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/Kconfig

@@ -348,7 +348,7 @@ config HW_RANDOM_HISTB
 
 config HW_RANDOM_ST
 	tristate "ST Microelectronics HW Random Number Generator support"
-	depends on HW_RANDOM && ARCH_STI
+	depends on HW_RANDOM && (ARCH_STI || COMPILE_TEST)
 	help
 	  This driver provides kernel-side support for the Random Number
 	  Generator hardware found on STi series of SoCs.