mfd: madera: Remove unused forward declaration of madera_codec_pdata

This forward declaration is redundant since the header including the
full data structure is included.
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

include/linux/mfd/madera/pdata.h

@@ -21,7 +21,6 @@
 
 struct gpio_desc;
 struct pinctrl_map;
-struct madera_codec_pdata;
 
 /**
  * struct madera_pdata - Configuration data for Madera devices