arm: mach-k3: am642: 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: Dave Gerlach <d-gerlach@ti.com>
diff --git a/board/ti/am64x/Kconfig b/board/ti/am64x/Kconfig
index 57527be..3dd5b54 100644
--- a/board/ti/am64x/Kconfig
+++ b/board/ti/am64x/Kconfig
@@ -19,6 +19,9 @@
 	select SYS_THUMB_BUILD
 	select K3_LOAD_SYSFW
 	select SOC_K3_AM642
+	select RAM
+	select SPL_RAM
+	select K3_DDRSS
 	imply SYS_K3_SPL_ATF
 
 endchoice