fix build for msm8916 platform

broken by commit 65f6b437

Bug: 79413773
Test: make
Change-Id: I33bc5d72b558a094374967cfda82470fcf34d16e
diff --git a/hal/msm8916/platform.c b/hal/msm8916/platform.c
index 1e6e95f..7f46b58 100644
--- a/hal/msm8916/platform.c
+++ b/hal/msm8916/platform.c
@@ -2522,9 +2522,9 @@
     return 0;
 }
 
-int platform_set_backend_cfg(const struct audio_device* adev,
-                             snd_device_t snd_device,
-                             const struct audio_backend_cfg *backend_cfg)
+int platform_set_backend_cfg(const struct audio_device* adev __unused,
+                             snd_device_t snd_device __unused,
+                             const struct audio_backend_cfg *backend_cfg __unused)
 {
     return -1;
 }
diff --git a/hal/msm8960/platform.c b/hal/msm8960/platform.c
index 5f8bd32..c3c211a 100644
--- a/hal/msm8960/platform.c
+++ b/hal/msm8960/platform.c
@@ -1371,9 +1371,9 @@
     return 0;
 }
 
-int platform_set_backend_cfg(const struct audio_device* adev,
-                             snd_device_t snd_device,
-                             const struct audio_backend_cfg *backend_cfg)
+int platform_set_backend_cfg(const struct audio_device* adev __unused,
+                             snd_device_t snd_device __unused,
+                             const struct audio_backend_cfg *backend_cfg __unused)
 {
     return -1;
 }