power: qpnp-smbcharger: fix battery presence

Currently the battery pres handler is setting the batt_pres status
variable to opposite of what it should be.

Fix this by storing the correct batt_pres status.

Change-Id: Ib6653bd2cad324c2d39b8be7f249718ab3f32ea7
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>