armv7R: K3: j721e: Add support for triggering ddr init from SPL

In SPL, DDR should be made available by the end of board_init_f()
so that apis in board_init_r() can use ddr. Adding support for
triggering DDR initialization from board_init_f().

Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
diff --git a/board/ti/j721e/Kconfig b/board/ti/j721e/Kconfig
index c2deb69..88097df 100644
--- a/board/ti/j721e/Kconfig
+++ b/board/ti/j721e/Kconfig
@@ -21,6 +21,7 @@
 	select K3_LOAD_SYSFW
 	select RAM
 	select SPL_RAM
+	select K3_J721E_DDRSS
 	imply SYS_K3_SPL_ATF
 
 endchoice