Move AudioMixer.h and BufferProviders.h into correct location

The implementation files are in libaudioprocessing,
thus the header files also belong there.

Test: make
Change-Id: I78ba4ed480413c0a1b871e80971ef5ce1d0c6755
diff --git a/include/media/AudioMixer.h b/include/media/AudioMixer.h
index de839c6..85ee950 120000
--- a/include/media/AudioMixer.h
+++ b/include/media/AudioMixer.h
@@ -1 +1 @@
-../../media/libaudioclient/include/media/AudioMixer.h
\ No newline at end of file
+../../media/libaudioprocessing/include/media/AudioMixer.h
\ No newline at end of file
diff --git a/include/media/BufferProviders.h b/include/media/BufferProviders.h
index 779bb15..778e1d8 120000
--- a/include/media/BufferProviders.h
+++ b/include/media/BufferProviders.h
@@ -1 +1 @@
-../../media/libmedia/include/media/BufferProviders.h
\ No newline at end of file
+../../media/libaudioprocessing/include/media/BufferProviders.h
\ No newline at end of file
diff --git a/media/libaudioclient/include/media/AudioMixer.h b/media/libaudioprocessing/include/media/AudioMixer.h
similarity index 100%
rename from media/libaudioclient/include/media/AudioMixer.h
rename to media/libaudioprocessing/include/media/AudioMixer.h
diff --git a/media/libmedia/include/media/BufferProviders.h b/media/libaudioprocessing/include/media/BufferProviders.h
similarity index 100%
rename from media/libmedia/include/media/BufferProviders.h
rename to media/libaudioprocessing/include/media/BufferProviders.h