mfd: axp20x: Remove second struct device * parameter for axp20x_match_device()

The first argument passed to axp20x_match_device(), struct axp20x_dev *,
already contains a pointer to the device. By rearranging some code,
moving the assignment of the pointer before axp20x_match_device() is
called, we can eliminate the second parameter.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>