rng: stm32: rename STM32 RNG driver

Rename the RNG driver as it is usable by other STM32 platforms
than the STM32MP1x ones. Rename CONFIG_RNG_STM32MP1 to
CONFIG_RNG_STM32

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Reviewed-by: Grzegorz Szymaszek <gszymaszek@short.pl>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
index 5deb5db..24666bf 100644
--- a/drivers/rng/Kconfig
+++ b/drivers/rng/Kconfig
@@ -48,11 +48,11 @@
 	  accessible to normal world but reserved and used by the OP-TEE
 	  to avoid the weakness of a software PRNG.
 
-config RNG_STM32MP1
-	bool "Enable random number generator for STM32MP1"
-	depends on ARCH_STM32MP
+config RNG_STM32
+	bool "Enable random number generator for STM32"
+	depends on ARCH_STM32 || ARCH_STM32MP
 	help
-	  Enable STM32MP1 rng driver.
+	  Enable STM32 rng driver.
 
 config RNG_ROCKCHIP
 	bool "Enable random number generator for rockchip crypto rng"