net/aoe: fix build on non-x86

While we are at it:

• remove BROKEN_... lines for FreeBSD versions out of support
• drop homegrown do-install in favour of USES=uidfix
• install kernel module into standard location
• attempt to fix the build on FreeBSD 13

Still doesn't work on FreeBSD 13.2. While it builds, the code now
fails at runtime, apparently when it tries to dereference vnet_entry_ifnet
in the line

IFNET_FOREACH(ifp)

in aoenet_xmitbcast.

PR: 239891