trivial patch to dm-linear.c

diff -ur linux-2.6.6-rc2-udm1-original/drivers/md/dm-linear.c linux-2.6.6-rc2-udm1-patched/drivers/md/dm-linear.c
@@ -115,7 +115,7 @@
 	return r;
 }
 
-void dm_linear_exit(void)
+void __exit dm_linear_exit(void)
 {
 	int r = dm_unregister_target(&linear_target);