overlays: i2c-rtc: Correct bq32000 property name

The DT property for the BQ32000 controlled by trickle-resistor-ohms
parameter should be "trickle-resistor-ohms", not "abracon,tc-resistor".

See: https://github.com/raspberrypi/linux/issues/6291



Signed-off-by: Phil Elwell <phil@raspberrypi.com>