hal: Fix EDID information

- Get EDID audio block info from a mixer control instead of a file.
- Fix a bug where the current sad is not updated in the for loop.

Bug: 9430906
Change-Id: I750e307ce1064eeb98d09ea8534a375252630841
diff --git a/hal/msm8960/platform.c b/hal/msm8960/platform.c
index c1c122d..e533f33 100644
--- a/hal/msm8960/platform.c
+++ b/hal/msm8960/platform.c
@@ -835,7 +835,7 @@
     return 0;
 }
 
-int platform_edid_get_max_channels(void)
+int platform_edid_get_max_channels(void *platform)
 {
     FILE *file;
     struct audio_block_header header;