regulator: fix regulator/consumer.h kernel-doc warning

Fix kernel-doc warning about internal/private data by marking it
as "private:" so that kernel-doc will ignore it.

Warning(include/linux/regulator/consumer.h:128): No description found for parameter 'ret'

Signed-off-by: Randy Dunlap <[e-mail]>
Acked-by: Mark Brown <[e-mail]>
Signed-off-by: Liam Girdwood <[e-mail]>

include/linux/regulator/consumer.h

···
 	const char *supply;
 	struct regulator *consumer;
 
-	/* Internal use */
+	/* private: Internal use */
 	int ret;
 };