arm64: dts: taimen: set fg-empty-voltage to 3.2V

Default fg-empty-voltage setting is 2850mV which is lower than the PMI
VBAT_TOO_LOW cut off and can lead to device brown out.
Raising fg-empty-voltage to 3.2V ensures device will perform a
controlled shutdown as 0% will be reported if battery voltage becomes
temporarily lower than this threshold.

Bug: 69274808
Change-Id: Idd3a1e2b067dd93d0503553e1da3c5d598dc8227
Signed-off-by: Thierry Strudel <tstrudel@google.com>