power: supply: s3c-adc-battery: Convert to GPIO descriptors

This converts the S3C ADC battery to use GPIO descriptors
instead of a global GPIO number for the charging completed
GPIO. Using the pattern from the GPIO charger we name this
GPIO line "charge-status" in the board file.

Cc: linux-samsung-soc@vger.kernel.org
Cc: Sergiy Kibrik <sakib@darkstar.site>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>