power: qpnp-fg-gen3: add support to configure batt_therm coefficients

Add support to configure battery thermal coefficients so that different
battery thermistors can be supported. These coefficients can be
configured via "qcom,battery-thermal-coefficients" device tree property.

CRs-Fixed: 2004461
Change-Id: Iff25acd397a68c31057dff4db1896d46e396adc6
Signed-off-by: Yingwei Zhao <cyizhao@codeaurora.org>