hal: add support for I2S based external modem

There are specific xml files used for I2S based external modem.
Add check to load the correct xml file.

For I2S based external modem, voice sample rate can be 8k or
16k based on vocoder type. Call csd client api to get the
correct sample rate to configure voice call.

Change-Id: Ie9799336620f49a890355be74fe1830eb348cabe
diff --git a/hal/platform_api.h b/hal/platform_api.h
index 81291a2..2ec6b50 100644
--- a/hal/platform_api.h
+++ b/hal/platform_api.h
@@ -44,6 +44,7 @@
 int platform_stop_voice_call(void *platform, uint32_t vsid);
 int platform_set_voice_volume(void *platform, int volume);
 int platform_set_mic_mute(void *platform, bool state);
+int platform_get_sample_rate(void *platform, uint32_t *rate);
 snd_device_t platform_get_output_snd_device(void *platform, audio_devices_t devices);
 snd_device_t platform_get_input_snd_device(void *platform, audio_devices_t out_device);
 int platform_set_hdmi_channels(void *platform, int channel_count);
@@ -63,7 +64,7 @@
 bool platform_listen_update_status(snd_device_t snd_device);
 
 /* From platform_info_parser.c */
-int platform_info_init(void);
+int platform_info_init(const char *filename);
 
 struct audio_offload_info_t;
 uint32_t platform_get_compress_offload_buffer_size(audio_offload_info_t* info);