dm: remove unused macro DM_MOD_NAME_SIZE

Signed-off-by: Wang Sheng-Hui <shhuiw@foxmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-target.c

@@ -16,8 +16,6 @@
 static LIST_HEAD(_targets);
 static DECLARE_RWSEM(_lock);
 
-#define DM_MOD_NAME_SIZE 32
-
 static inline struct target_type *__find_target_type(const char *name)
 {
 	struct target_type *tt;