rng: Add Turris Mox rTWM RNG driver

A RNG driver for Armada 3720 boards running the Turris Mox rWTM firmware
from CZ.NIC in the secure processor.

Signed-off-by: Max Resch <resch.max@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig
index a89c899..cd72852 100644
--- a/drivers/rng/Kconfig
+++ b/drivers/rng/Kconfig
@@ -105,4 +105,12 @@
 	help
 	  Enable True Random Number Generator in StarFive JH7110 SoCs.
 
+config RNG_TURRIS_RWTM
+	bool "Turris Mox TRNG in Secure Processor"
+	depends on DM_RNG && ARMADA_3700
+	help
+	  Use TRNG in Turris Mox Secure Processor Firmware. Can be used
+	  on other Armada-3700 devices (like EspressoBin) if Secure
+	  Firmware from CZ.NIC is used.
+
 endif