afs: fix afs_linux_mmap fstrace entry
The format string for CM_TRACE_GMAP takes 4 substitutions, but
afs_linux_mmap only supplies 3. This results in malformed output from
fstrace:
Type mismatch, using raw print.
Gn_map vp 0x%lx addr 0x%lx len 0x%x off 0x%x (afs / zcm)raw op
701087775, time 715.322573, pid 9644
p0:0xc0a66ec0 p1:0x8b81a000 p2:131072
Repair the recording of CM_TRACE_GMAP.
Change-Id: I2b7592e68cb42f5ae490ee8771558e5cc5a2181e
Reviewed-on: https://gerrit.openafs.org/14168
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>