power: qpnp-fg: fix fg_is_batt_id_valid

fg_is_batt_id_valid is currently checking the incorrect
bit when verifiying if the battery has been identified.

Fix this by adding a definition for the BATT_IDED bit 3.

Change-Id: I52423ac2bcb3887344cba41cce6118c8ed96c812
Signed-off-by: David Keitel <dkeitel@codeaurora.org>