regulator: Fix trivial spelling

The word 'descriptor' is misspelled throughout the tree.

Fix it up accordingly:
    decriptors -> descriptors

Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/20200609124610.3445662-10-kieran.bingham+renesas@ideasonboard.com


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