arm: keystone: Move cmd_ddr3 to a common place

Move cmd_ddr3 to cmd/ti in order to make
it build for non-keystone TI platforms.

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
[trini: Rename to ddr3.c not cmd_ddr3.c]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index 83dc778..faa8bc6 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1184,6 +1184,8 @@
 
 endmenu
 
+source "cmd/ti/Kconfig"
+
 config CMD_BOOTSTAGE
 	bool "Enable the 'bootstage' command"
 	depends on BOOTSTAGE