NFSD: Remove definition for trace_nfsd_file_gc_recent

Event nfsd_file_gc_recent was added by commit 6491212 ("nfsd:
filecache: introduce NFSD_FILE_RECENT") but never used.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Closes: https://lore.kernel.org/linux-nfs/5ccae2f9-1560-4ac5-b506-b235ed4e4f4f@oracle.com/T/#t
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

Author: chucklever

fs/nfsd/trace.h

@@ -1377,7 +1377,6 @@ DEFINE_EVENT(nfsd_file_lruwalk_class, name,				\
 	TP_ARGS(removed, remaining))
 
 DEFINE_NFSD_FILE_LRUWALK_EVENT(nfsd_file_gc_removed);
-DEFINE_NFSD_FILE_LRUWALK_EVENT(nfsd_file_gc_recent);
 DEFINE_NFSD_FILE_LRUWALK_EVENT(nfsd_file_shrinker_removed);
 
 TRACE_EVENT(nfsd_file_close,