ASoC: Implement WM8994 OPCLK support

The WM8994 can output a clock derived from its internal SYSCLK, called
OPCLK.  The rate can be selected as a sysclk, with a division from the
SYSCLK rate specified (multiplied by 10 since a division of 5.5 is
supported) and the clock can be disabled by specifying a divisor of
zero.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
diff --git a/sound/soc/codecs/wm8994.h b/sound/soc/codecs/wm8994.h
index 7072dc5..2e0ca67 100644
--- a/sound/soc/codecs/wm8994.h
+++ b/sound/soc/codecs/wm8994.h
@@ -20,6 +20,9 @@
 #define WM8994_SYSCLK_FLL1  3
 #define WM8994_SYSCLK_FLL2  4
 
+/* OPCLK is also configured with set_dai_sysclk, specify division*10 as rate. */
+#define WM8994_SYSCLK_OPCLK 5
+
 #define WM8994_FLL1 1
 #define WM8994_FLL2 2