power: supply: sbs-battery: Use gpio_desc and sleeping calls for battery detect

Switch to using new gpio_desc interface and devm gpio get calls to
automatically manage gpio resource. Use gpiod_get_value which handles
active high / low calls.

If gpio_detect is set then force loading of the driver as it is
reasonable to assume that the battery may not be present.

Update the is_present flag immediately in the IRQ.

Remove legacy gpio specification from platform data.

Signed-off-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: Sebastian Reichel <sre@kernel.org>