param: fix module param locks when !CONFIG_SYSFS.

As Dan Streetman points out, the entire point of locking for is to
stop sysfs accesses, so they're elided entirely in the !SYSFS case.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/kernel/module.c b/kernel/module.c
index 8ec33ce..b4994ad 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1820,6 +1820,10 @@
 	mod_kobject_put(mod);
 }
 
+static void init_param_lock(struct module *mod)
+{
+	mutex_init(&mod->param_lock);
+}
 #else /* !CONFIG_SYSFS */
 
 static int mod_sysfs_setup(struct module *mod,
@@ -1842,6 +1846,9 @@
 {
 }
 
+static void init_param_lock(struct module *mod)
+{
+}
 #endif /* CONFIG_SYSFS */
 
 static void mod_sysfs_teardown(struct module *mod)
@@ -3442,7 +3449,7 @@
 	if (err)
 		goto unlink_mod;
 
-	mutex_init(&mod->param_lock);
+	init_param_lock(mod);
 
 	/* Now we've got everything in the final locations, we can
 	 * find optional sections. */