regulator: Fix regulator_summary for deviceless consumers

BugLink: http://bugs.launchpad.net/bugs/1673538

commit e42a46b6 upstream.

It is allowed to call regulator_get with a NULL dev argument
(_regulator_get explicitly checks for it) but this causes an error later
when printing /sys/kernel/debug/regulator_summary.

Fix this by explicitly handling "deviceless" consumers in the debugfs code.
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/regulator/core.c

@@ -4273,12 +4273,13 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 	seq_puts(s, "\n");
 
 	list_for_each_entry(consumer, &rdev->consumer_list, list) {
-		if (consumer->dev->class == &regulator_class)
+		if (consumer->dev && consumer->dev->class == &regulator_class)
 			continue;
 
 		seq_printf(s, "%*s%-*s ",
 			   (level + 1) * 3 + 1, "",
-			   30 - (level + 1) * 3, dev_name(consumer->dev));
+			   30 - (level + 1) * 3,
+			   consumer->dev ? dev_name(consumer->dev) : "deviceless");
 
 		switch (rdev->desc->type) {
 		case REGULATOR_VOLTAGE: