IIO: fix build error in lp8788-charger.c

Turns out that consumer.h needs to include types.h on some platforms to
build properly (like powerpc).
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/iio/consumer.h

@@ -9,6 +9,8 @@
  */
 #ifndef _IIO_INKERN_CONSUMER_H_
 #define _IIO_INKERN_CONSUMER_H_
+
+#include <linux/types.h>
 #include <linux/iio/types.h>
 
 struct iio_dev;