[ALSA] es18xx: Enable wavetable input from ESS chips

This patch enables wavetable chips ES689/ES69X connected to
ESS ES18xx chips. The wavetable chip uses FM DAC if the clock signal
from the wavetable is active.
It has no effect if there is no ESS wavetable chip present.
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>

sound/isa/es18xx.c

@@ -1442,6 +1442,8 @@ static int __devinit snd_es18xx_initialize(struct snd_es18xx *chip)
 		snd_es18xx_write(chip, 0xB2, 0x50);
 		/* Enable MPU and hardware volume interrupt */
 		snd_es18xx_mixer_write(chip, 0x64, 0x42);
+		/* Enable ESS wavetable input */
+		snd_es18xx_mixer_bits(chip, 0x48, 0x10, 0x10);
 	}
 	else {
 		int irqmask, dma1mask, dma2mask;