regulator: gpio: Fix trivial spelling

decriptor -> descriptor.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Link: https://lore.kernel.org/r/20200609124610.3445662-17-kieran.bingham+renesas@ideasonboard.com


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