regulator: use consumer->supply_name in debugfs/regulator_summary

Make it easier to identify regulator consumers when consumer device
uses more than one supply.

Before:

  regulator                      ena use open bypass voltage current min     max
 -----------------------------------------------------------------------------------
  regulator-dummy                  1   0    2      0     0mV     0mA 0mV     0mV
     1-0010                                                          0mV     0mV
     1-0010                                                          0mV     0mV

After:

  regulator                      ena use open bypass voltage current min     max
 -----------------------------------------------------------------------------------
  regulator-dummy                  1   0    2      0     0mV     0mA 0mV     0mV
     1-0010-vccio                                                    0mV     0mV
     1-0010-vcc33                                                    0mV     0mV
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Link: https://lore.kernel.org/r/731a4b299c6ae0ee9d8995157600a3477f21a36c.1585959068.git.mirq-linux@rere.qmqm.plSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/core.c

@@ -5496,6 +5496,7 @@ static void regulator_summary_show_subtree(struct seq_file *s,
 		seq_printf(s, "%*s%-*s ",
 			   (level + 1) * 3 + 1, "",
 			   30 - (level + 1) * 3,
+			   consumer->supply_name ? consumer->supply_name :
 			   consumer->dev ? dev_name(consumer->dev) : "deviceless");
 
 		switch (rdev->desc->type) {