power: qpnp-fg: fix reading OCV junction coefficients

Commit 5d82a81e ("power: qpnp-fg: add support for restoring
battery information") created a bug in getting OCV junction
coefficients p1p2 and p2p3 from the data read from same offset.
Fix it.

Change-Id: Icf106e612a890b378fd1993eceac71b1f21770d0
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>