ram: k3-ddrss: Introduce top-level CONFIG_K3_DDRSS

Create a new CONFIG_K3_DDRSS option to select the common parts of the
k3-ddrss driver. Also introduce a choice that depends on the top level
option to select CONFIG_K3_J721E_DDRSS for j721e support, and update
corresponding Kconfig as required.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
diff --git a/drivers/ram/Kconfig b/drivers/ram/Kconfig
index a270e13..4e4e7a9 100644
--- a/drivers/ram/Kconfig
+++ b/drivers/ram/Kconfig
@@ -54,9 +54,16 @@
 	  config add support for the initialization of the external
 	  SDRAM devices connected to DDR subsystem.
 
+config K3_DDRSS
+	bool "Enable K3 DDRSS support"
+	depends on RAM
+
+choice
+	depends on K3_DDRSS
+	prompt "K3 DDRSS Arch Support"
+
 config K3_J721E_DDRSS
 	bool "Enable J721E DDRSS support"
-	depends on RAM
 	help
 	  The J721E DDR subsystem comprises DDR controller, DDR PHY and
 	  wrapper logic to integrate these blocks in the device. The DDR
@@ -65,6 +72,8 @@
 	  Enabling this config adds support for the DDR memory controller
 	  on J721E family of SoCs.
 
+endchoice
+
 config IMXRT_SDRAM
 	bool "Enable i.MXRT SDRAM support"
 	depends on RAM