regulator: sy7636a: Use rdev_get_drvdata at proper place

At the context with *rdev, use rdev_get_drvdata() is more intuitive.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Alistair Francis <alistair@alistair23.me>
Link: https://lore.kernel.org/r/20210616034458.3499522-3-axel.lin@ingics.com


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