In many cases, when fw is installed in /lib/firmware, some of it ends up
in the initramfs. In those situations, mkinitfs should run so that the
initramfs gets the latest fw. This will result in mkinitfs possibly
running in cases where it doesn't matter (i.e. device has fw in
/lib/firmware but none is used in the initramfs), but I think the
trade-off is worth it.

This also breaks the triggers= line into multiple lines so that it's
easier to review/maintain. We can't prepend whitespace on these lines
since the apkbuild parser expects dirs to be separated by ":"