(This change was supposed to be included in r277508.)
sys/boot/i386/libfirewire/firewire.c:
Fix configuration ROM generation count wrapping logic
so that the generation count is never outside of
allowed limits (0x2 -> 0xF).
Submitted by: gibbs
MFC after: 1 week
MFC with: 277508
Sponsored by: Spectra Logic
MFSpectraBSD: 1110685 on 2015/01/05