power: supply: bq25890: Check for bq->charger being NULL in external_power_changed

2 jobs for bq-null in 69 minutes and 45 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Build
passed build:aarch64 #376872
librem5

00:31:40

passed build:deb #376873
librem5:arm64

01:09:45