hal: add support to override volume gain to step mapping table

- if customer mapping is added in platform info file, use that
- in absence of customer table use default mapping

CRs-Fixed: 1089771
Change-Id: I4bf8bcf1913f16ad6298ff1f3fa5dd649c889b2a
diff --git a/hal/msm8960/platform.c b/hal/msm8960/platform.c
index 33bbc2f..31d86f4 100644
--- a/hal/msm8960/platform.c
+++ b/hal/msm8960/platform.c
@@ -1340,3 +1340,13 @@
     return false;
 }
 
+bool platform_add_gain_level_mapping(struct amp_db_and_gain_table *tbl_entry __unused)
+{
+    return false;
+}
+
+int platform_get_gain_level_mapping(struct amp_db_and_gain_table *mapping_tbl __unused,
+                                    int table_size __unused)
+{
+    return 0;
+}