ram: k3-ddrss: Allow use of dt provided initial frequency

Allow device tree to provide ti,ddr-freq0 to be used as the initial DDR
frequency that is set for lpddr4 before initialization of the
controller. Make this optional and continue to use PLL bypass frequency
as is done currently if ti,ddr-freq0 is not provided.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
diff --git a/doc/device-tree-bindings/memory-controller/k3-j721e-ddrss.txt b/doc/device-tree-bindings/memory-controller/k3-j721e-ddrss.txt
index df3290a..1ea0a70 100644
--- a/doc/device-tree-bindings/memory-controller/k3-j721e-ddrss.txt
+++ b/doc/device-tree-bindings/memory-controller/k3-j721e-ddrss.txt
@@ -39,6 +39,8 @@
 - reg:			Must add "ss" to list if the above ss region is included.
 - ti,ecc-enable:	Boolean flag to enable ECC. This will reduce available DDR
 			by 1/9.
+- ti,ddr-freq0:		Initial frequency set point, if not provided PLL bypass
+			frequency will be used.
 
 Example (J721E):
 ================