ram: starfive: add ddr driver

Add driver for StarFive JH7110 to support ddr initialization in SPL.

Signed-off-by: Yanhong Wang <yanhong.wang@starfivetech.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
diff --git a/drivers/ram/starfive/Kconfig b/drivers/ram/starfive/Kconfig
new file mode 100644
index 0000000..80c7900
--- /dev/null
+++ b/drivers/ram/starfive/Kconfig
@@ -0,0 +1,5 @@
+config SPL_STARFIVE_DDR
+	bool "StarFive DDR driver in SPL"
+	depends on SPL_RAM && STARFIVE_JH7110
+	help
+	  This enables DDR support for the platforms based on StarFive JH7110 SoC.