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/fs/hpfs/inode.c b/fs/hpfs/inode.c
index 39a1bfb..fe703ae 100644
--- a/fs/hpfs/inode.c
+++ b/fs/hpfs/inode.c
@@ -6,6 +6,7 @@
  *  inode VFS functions
  */
 
+#include <linux/smp_lock.h>
 #include "hpfs_fn.h"
 
 void hpfs_init_inode(struct inode *i)