module: Drop redundant declaration of struct module

Struct module is already declared at the beginning of the file, no
need to declare it again.
Signed-off-by: Jean Delvare <jdelvare@suse.de>
Fixes: 93c2e105 ("module: Optimize __module_address() using a latched RB-tree")
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jessica Yu <jeyu@redhat.com>

include/linux/module.h

@@ -282,8 +282,6 @@ enum module_state {
 	MODULE_STATE_UNFORMED,	/* Still setting it up. */
 };
 
-struct module;
-
 struct mod_tree_node {
 	struct module *mod;
 	struct latch_tree_node node;