power: qpnp-fg: fix null pointer dereference in suspend

Currently the driver uses the drvdata to get the chip data structure
during the pm ops for suspend. However, the drvdata is not set during
probe, so this ends up being a null pointer exception.

Fix this by setting the correct drvdata during probe.

CRs-Fixed: 709566
Change-Id: I978f3039c945d93cf43e6d53c5ace8a4d6105af5
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>