mfd: max77686: Use of_device_get_match_data() helper

Use the generic helper to get the matched of_device_id .data, instead of
open coding it.

The driver was checking if matching the OF node with the driver's OF table
was failing, but this doesn't make too much sense since this can't happen
in practice. The fact the probe function was called, means OF registered a
device with a valid compatible string so a of_device_get_match_data() call
will always succeed. So just remove this unneeded check.

Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Tested-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>