power: qpnp-fg-gen4: Fix debug battery id reporting

Currently, for getting debug battery id thresholds, only lower
threshold register is read twice. Fix this by reading higher
threshold register.

Change-Id: I9dee9f79bd0ccd1f73694e30e399f757815e139f
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>