ram: k3-ddrss: lpddr4_structs_if.h: Add a pointer to ddr instance

Add a pointer to ddr instance int the lpddr4_privatedata_s structure for
supporting mutliple instances of DDR in the drivers.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
diff --git a/drivers/ram/k3-ddrss/lpddr4_structs_if.h b/drivers/ram/k3-ddrss/lpddr4_structs_if.h
index e41cbb7..f2f1210 100644
--- a/drivers/ram/k3-ddrss/lpddr4_structs_if.h
+++ b/drivers/ram/k3-ddrss/lpddr4_structs_if.h
@@ -24,6 +24,7 @@
 	lpddr4_infocallback infohandler;
 	lpddr4_ctlcallback ctlinterrupthandler;
 	lpddr4_phyindepcallback phyindepinterrupthandler;
+	void *ddr_instance;
 };
 
 struct lpddr4_debuginfo_s {