rt2x00: change function pointers for register accessors

This prepares the driver for changing all the 'read' register accessors
to return the value instead of passing it by reference. Since a lot
of them are used in callbacks, this takes care of the callbacks first,
adding a couple of helpers that will be removed again one at a time.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c b/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c
index 964aefd..4a1bca1b 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2x00debug.c
@@ -460,7 +460,7 @@ static ssize_t rt2x00debug_read_##__name(struct file *file,	\
 	if (debug->__name.flags & RT2X00DEBUGFS_OFFSET)		\
 		index *= debug->__name.word_size;		\
 								\
-	debug->__name.read(intf->rt2x00dev, index, &value);	\
+	value = debug->__name.read(intf->rt2x00dev, index);	\
 								\
 	size = sprintf(line, __format, value);			\
 								\