arm64: dts: imx8mq-librem5: fix camera supplies description

CAMERA_PWR_EN controls different power supplies that cameras will use.
Describe that appropriately.
2 jobs for pureos/byzantium in 67 minutes and 42 seconds
Status Job ID Name Coverage
  Build
passed #355917
librem5
build:aarch64

00:29:44

passed #355918
librem5:arm64
build:deb

01:07:41