target,platform: msm_shared: correct sdcc ddr register

sdcc ddr config register has changed for new targets.
ensure that correct register is read.

Change-Id: I8893f05c4775073921a1cef480284d18ff0d70bc
diff --git a/include/target.h b/include/target.h
index d0d830d..62369ed 100644
--- a/include/target.h
+++ b/include/target.h
@@ -93,6 +93,7 @@
 
 struct qmp_reg *target_get_qmp_settings();
 int target_get_qmp_regsize();
+uint32_t target_ddr_cfg_reg();
 
 #if PON_VIB_SUPPORT
 void get_vibration_type();