Use the long version of the bwfm(4) firmware path, which includes the

Use the long version of the bwfm(4) firmware path, which includes the
board's compatible string, when printing an error about not being able
to load the firmware.  Since most NVRAM files are board- or package-
specific, having the compatible makes it easier for us to find the
correct files, so that we can add them to the bwfm-firmware port.

ok kurt@