power: qpnp-fg: support battery hotswapping

Currently the fuel gauge driver is ignorant to battery hotswaps (switching
the battery while the device is powered from a different source). This
can cause issues because the battery profile is reloaded from OTP upon
battery insertions. If a custom profile was loaded, it will be
overwritten by the one loaded in OTP.

Fix this by rerunning the battery profile loading function whenever the
battery is inserted.

CRs-Fixed: 720242
Change-Id: I1ae877d39a2a81c97243386e8683e63bd01a45e4
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>