hal: add support for pcm_ioctl() api

- Tinyalsa doesn't expose an api to call
  ioctls exposed by the audio drivers.
- Add pcm_ioctl() api to support pcm ioctl.

Change-Id: I448252e8d3347257a73c56bc8ed341abc2dd2dab
diff --git a/hal/audio_hw.c b/hal/audio_hw.c
index 37bbcba..f0a5a97 100644
--- a/hal/audio_hw.c
+++ b/hal/audio_hw.c
@@ -2913,6 +2913,19 @@
     return 0;
 }
 
+int pcm_ioctl(struct pcm *pcm, int request, ...)
+{
+    va_list ap;
+    void * arg;
+    int pcm_fd = *(int*)pcm;
+
+    va_start(ap, request);
+    arg = va_arg(ap, void *);
+    va_end(ap);
+
+    return ioctl(pcm_fd, request, arg);
+}
+
 static struct hw_module_methods_t hal_module_methods = {
     .open = adev_open,
 };