power: gemini-poweroff: Avoid spurious poweroff

On the D-Link DIR-685 we get spurious poweroff from
infrared. Since that block (CIR) doesn't even have a
driver this can be safely ignored, we can revisit this
code once we have a device supporting CIR.

On the D-Link DNS-313 we get spurious poweroff from
the power button. This appears to be an initialization
issue: we need to enable the block (start the state
machine) before we clear any dangling IRQ.

This patch fixes both issues.

Fixes: f7a388d6 ("power: reset: Add a driver for the Gemini poweroff")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>