Remove some duplicated sys/conf/files* entries.

net80211/ieee80211_ageq.c was present twice in sys/conf/files so leave the
correctly sorted one. dev/wpi/if_wpi.c was present in sys/conf/files as well
as sys/conf/files.amd64 and sys/conf/files.i386 so prefer the sys/conf/files
entry.

Reviewed by: allanjude, rstone