hal: Fix DisplayPort Passthrough Mixer Command

Address the incorrect mixer command being used
for setting the backend format

Change-Id: I871d3d731eb80e2cd24feaa116ad66dfd4dbfe4c
CRs-Fixed: 2002322
diff --git a/hal/msm8916/platform.c b/hal/msm8916/platform.c
index e76398d..a9ffa14 100644
--- a/hal/msm8916/platform.c
+++ b/hal/msm8916/platform.c
@@ -5046,7 +5046,7 @@
         ext_disp_format = "HDMI RX Format";
         set_ext_disp_format = true;
     } else if (backend_idx == DISP_PORT_RX_BACKEND) {
-        ext_disp_format = "Display Port Rx Format";
+        ext_disp_format = "Display Port RX Format";
         set_ext_disp_format = true;
     } else {
         ALOGV("%s: Format doesnt have to be set", __func__);