Occasionally the setup function will be called multiple times. Only request
the gpio the first time otherwise -EBUSY will occur on subsequent calls to
setup.
Reported-by: NJoseph Bell <joe@iachieved.it>
Signed-off-by: NMichael Welling <mwelling@ieee.org>
Signed-off-by: NMark Brown <broonie@kernel.org>