OMAPDSS: hdmi.h: Add HDMI_AUDIO_LAYOUT_6CH enum value

The OMAP5 HDMI audio implementation needs HDMI_AUDIO_LAYOUT_6CH in
hdmi_core_audio_layout enum. I found the correct value from ti-linux
3.8 tree.
Signed-off-by: NJyri Sarha <jsarha@ti.com>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/omap2/dss/hdmi.h

@@ -153,7 +153,8 @@ enum hdmi_audio_blk_strt_end_sig {
 
 enum hdmi_core_audio_layout {
 	HDMI_AUDIO_LAYOUT_2CH = 0,
-	HDMI_AUDIO_LAYOUT_8CH = 1
+	HDMI_AUDIO_LAYOUT_8CH = 1,
+	HDMI_AUDIO_LAYOUT_6CH = 2
 };
 
 enum hdmi_core_cts_mode {