ram: add ddr4 dual x8 configuration

the aspeed ddr sdram controller needs to know if the memory chip mounted on
the board is dual x8 die or not. Or it may get the wrong size of the
memory space.

Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
Reviewed-by: Ryan Chen <ryan_chen@aspeedtech.com>
diff --git a/drivers/ram/Kconfig b/drivers/ram/Kconfig
index a0e859a..a270e13 100644
--- a/drivers/ram/Kconfig
+++ b/drivers/ram/Kconfig
@@ -73,6 +73,7 @@
 	  to support external memories like sdram, psram & nand.
 	  This driver is for the sdram memory interface with the SEMC.
 
+source "drivers/ram/aspeed/Kconfig"
 source "drivers/ram/rockchip/Kconfig"
 source "drivers/ram/sifive/Kconfig"
 source "drivers/ram/stm32mp1/Kconfig"