gpio: search for gpio label if gpio is not found through bank name

gpio: search for gpio label if gpio is not found through bank name

dm_gpio_lookup_name() searches for a gpio through
the bank name. But we have also gpio labels, and it
makes sense to search for a gpio also in the labels
we have defined, if no gpio is found through the
bank name definition.

This is useful for example if you have a wp pin on
different gpios on different board versions.

If dm_gpio_lookup_name() searches also for the gpio labels,
you can give the gpio an unique label name and search
for this label, and do not need to differ between
board revisions.

Signed-off-by: Heiko Schocher <[email protected]>
Reviewed-by: Simon Glass <[email protected]>
[trini: Don't enable by default]
Signed-off-by: Tom Rini <[email protected]>