headers: smp_lock.h redux

* Remove smp_lock.h from files which don't need it (including some headers!)
* Add smp_lock.h to files which do need it
* Make smp_lock.h include conditional in hardirq.h
  It's needed only for one kernel_locked() usage which is under CONFIG_PREEMPT

  This will make hardirq.h inclusion cheaper for every PREEMPT=n config
  (which includes allmodconfig/allyesconfig, BTW)

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/net/wanrouter/wanmain.c b/net/wanrouter/wanmain.c
index 466e2d2..258daa8 100644
--- a/net/wanrouter/wanmain.c
+++ b/net/wanrouter/wanmain.c
@@ -48,6 +48,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>	/* support for loadable modules */
 #include <linux/slab.h>		/* kmalloc(), kfree() */
+#include <linux/smp_lock.h>
 #include <linux/mm.h>
 #include <linux/string.h>	/* inline mem*, str* functions */