power: qpnp-fg-gen4: Set default values for {dis}charging Ki coefficients

Set default values for the low, medium, and high gain Ki coefficients
for both charging and discharging states.

Change-Id: I30b164045187ea1f995522523fcadb31b0c04873
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>