Bluetooth: Disable lpm from hci for PR and Rome based targets

- Disable lpm support from HCI layer for Pronto and Rome based
  targets as LPM is already handled by other mechanism.

CRs-Fixed: 890003
Change-Id: I69e81d60748b2a00840479aea378f3c6d118a575
diff --git a/libbt-vendor/src/bt_vendor_qcom.c b/libbt-vendor/src/bt_vendor_qcom.c
index 838efc0..cd17077 100644
--- a/libbt-vendor/src/bt_vendor_qcom.c
+++ b/libbt-vendor/src/bt_vendor_qcom.c
@@ -942,8 +942,9 @@
                     bt_vendor_cbacks->lpm_cb(BT_VND_OP_RESULT_SUCCESS);
             }
             else {
+                // respond with failure as it's already handled by other mechanism
                 if (bt_vendor_cbacks)
-                    bt_vendor_cbacks->lpm_cb(BT_VND_OP_RESULT_SUCCESS); //dummy
+                    bt_vendor_cbacks->lpm_cb(BT_VND_OP_RESULT_FAIL);
             }
             break;