Fix u-boot config saving on Raspberry Pi 4

[darkain]

More details can be found on Bugzilla:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=268630#c17

[lwhsu]

Please note that the PORTREVISION needs to be bumped here.

[darkain]

PORTREVISION changes would get into murky territory because this port is a child-port of another port. Would we carry that indefinitely, or would changes to the parent-port be cognitive to this PORTREVISION and reset it when updating there? Also generally speaking, this isn't even a normal "installable" port, it is part of the build process of generating FreeBSD SD card image files.

[bsdimp]

I'd be tempted to just do a PORTREVISION in the parent port. That would go away with the next update.

[arrowd]

The common solution for this is that master ports should always have PORTREVISION variable, like

PORTREVISION?= 0

This allows for slave ports to have their own revisions independent of master.

[diizzyy]

This still needs to go via bugzilla to land