power: pm8921-charger: Enable Battery Temperature Interrupts

Handle temperature related interrupts to disable or re-enable
charging of battery for JEITA compliance. If the temperature
drops or rises beyond the respective temperature level the falling
edge of the BAT_TEMP_OK_IRQ is triggered and external charging
is disabled. Once the temperature returns to an acceptable level
the rising edge of the interrupt triggers and the handler enables
external charging again.

CRs-Fixed: 315196
Change-Id: I7d001cde2ee9ac96e2321202fbf76ad03a986536
Signed-off-by: David Keitel <dkeitel@codeaurora.org>