power: supply: bq27xxx: do not report bogus zero values

On the bq27x00 and bq27x10 variants, a number of conditions may reset the value
stored in the NAC register. This will cause capacity, energy, and charge to
report the value 0, even when the battery is full. On the other hand, the chip
also provides a flag, EDVF, which accurately detects the true battery empty
condition, when capacity, charge, and energy are really 0.  Therefore, discard
readings for these properties if their value is 0 while EDVF is unset.

Tested on the Nokia N900 with bq27200.

Signed-off-by: Sicelo A. Mhlongo <absicsz@gmail.com>
Link: https://lore.kernel.org/r/20250207220605.106768-1-absicsz@gmail.com


Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>