power: qpnp-linear-charger: Use FORCE_BATT_ON to disable charging

When there is no battery present the charger FSM does not get disabled
even with the CHG_EN bit. Use the FORCE_BATT_ON bit along with the
CHG_EN bit to disable the charging FSM.

While at it, do not set the online property as its set by the USB
driver.

CRs-Fixed: 635784
Change-Id: Ie33e1a9ccc7781606829a5ef9a310b0c5de330d1
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>