dev_printk(): constify the `dev' argument

Add const markings to dev_name and dev_driver_string to make it clear that
dev_printk doesn't modify dev.  This is a prerequisite to adding more
const markings to other functions make it clearer, which functions can
modify dev and which can't.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 068aa1c..44bad73 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -53,7 +53,7 @@
  * it is attached to.  If it is not attached to a bus either, an empty
  * string will be returned.
  */
-const char *dev_driver_string(struct device *dev)
+const char *dev_driver_string(const struct device *dev)
 {
 	return dev->driver ? dev->driver->name :
 			(dev->bus ? dev->bus->name :