sh: sh_dac_audio fixes

From: Magnus Damm <[email protected]>

This patch modifies sh_dac_audio in the following ways:
- use high resolution timer instead of TMU1
- fix cpu/dac.h include
- add CONFIG_SH_HP6XX ifdefs
- add future rewrite comment

---

 sound/oss/Kconfig        |    2 -
 sound/oss/sh_dac_audio.c |   81 +++++++++++++++++-----------------------------
 2 files changed, 32 insertions(+), 51 deletions(-)

@@ -561,7 +561,7 @@ endif	# SOUND_OSS
 
 config SOUND_SH_DAC_AUDIO
 	tristate "SuperH DAC audio support"
-	depends on CPU_SH3
+	depends on CPU_SH3 && HIGH_RES_TIMERS
 
 config SOUND_SH_DAC_AUDIO_CHANNEL
 	int "DAC channel"