re: panic: kernel diagnostic assertion "offset < map->dm_maps" failed

[matthew green]

i'm pretty sure i've solved this properly this attempt, but
review on this change would be appreciated.

   https://www.netbsd.org/~mrg/if_rge.c.v3.diff

it includes a potential way to avoid wm(4) calling panic() if
bus_dmamap_load*() fails..


.mrg.