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.pl


Signed-off-by: Mark Brown <broonie@kernel.org>