hal: Fix compilation issue during send audio calibration for hfp use case

Fix multiple definition compilation error for send_audio_calibration_hfp()
API.

Change-Id: I5bc75b0165e2f6a9a532d176b347c6adf442c067
diff --git a/hal/msm8916/platform.c b/hal/msm8916/platform.c
index 2f8a6f2..e5c2ab2 100644
--- a/hal/msm8916/platform.c
+++ b/hal/msm8916/platform.c
@@ -3780,6 +3780,12 @@
     return 0;
 }
 
+int platform_send_audio_calibration_hfp(void *platform __unused,
+                                        snd_device_t snd_device __unused)
+{
+    return 0;
+}
+
 int platform_switch_voice_call_device_pre(void *platform)
 {
     struct platform_data *my_data = (struct platform_data *)platform;
diff --git a/hal/msm8960/platform.c b/hal/msm8960/platform.c
index 94c0a62..439b6d7 100644
--- a/hal/msm8960/platform.c
+++ b/hal/msm8960/platform.c
@@ -536,6 +536,12 @@
     return -ENOSYS;
 }
 
+int platform_send_audio_calibration_hfp(void *platform __unused,
+                                        snd_device_t snd_device __unused)
+{
+    return 0;
+}
+
 int platform_send_audio_calibration(void *platform, struct audio_usecase *usecase,
                                     int app_type __unused)
 {