Properly lock accesss to the firewire_comm->devices list.

sys/dev/firewire/firewire.c:
Add missing FW_GLOCK/UNLOCK() usage to fw_noderesolve_nodeid().

sys/dev/firewire/firewire.c:
sys/dev/firewire/fwmem.c:
Remove no-op splfw() calls from functions that have been
audited for proper lock usage.

Submitted by: gibbs
MFC after: 1 week
Sponsored by: Spectra Logic
MFSpectraBSD: 1110992 on 2015/01/06