[GFS2] Remove unused GL_DUMP flag

There is no way to set the GL_DUMP flag, and in any case the
same thing can be done with systemtap if required for debugging,
so this removes it.

Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glock.c

@@ -1244,9 +1244,6 @@ restart:
 
 	clear_bit(GLF_PREFETCH, &gl->gl_flags);
 
-	if (error == GLR_TRYFAILED && (gh->gh_flags & GL_DUMP))
-		dump_glock(gl);
-
 	return error;
 }