ram: move aspeed ram driver into drivers/ directory

to improve the maintainability.  It is more easier to modify and add
configurations of the driver in the centralized ram driver directory.

Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com>
Reviewed-by: Ryan Chen <ryan_chen@aspeedtech.com>
diff --git a/drivers/ram/Makefile b/drivers/ram/Makefile
index d685a57..209a78c 100644
--- a/drivers/ram/Makefile
+++ b/drivers/ram/Makefile
@@ -14,6 +14,7 @@
 
 obj-$(CONFIG_K3_AM654_DDRSS) += k3-am654-ddrss.o
 obj-$(CONFIG_ARCH_MEDIATEK) += mediatek/
+obj-$(CONFIG_ARCH_ASPEED) += aspeed/
 obj-$(CONFIG_K3_J721E_DDRSS) += k3-j721e/
 
 obj-$(CONFIG_IMXRT_SDRAM) += imxrt_sdram.o