btrfs: do not directly include rwlock_types.h

There is already an error inside that header:

#if !defined(__LINUX_SPINLOCK_TYPES_H)
# error "Do not include directly, include spinlock_types.h"
#endif

Thankfully it never get triggered as some other headers have already
included spinlock_types.h.

However clangd would still do a proper warning on that if only
extent_map.h is opened.
Fix it by using spinlock_types.h instead.

Reviewed-by: Filipe Manana <[e-mail]>
Signed-off-by: Qu Wenruo <[e-mail]>
Reviewed-by: David Sterba <[e-mail]>
Signed-off-by: David Sterba <[e-mail]>

fs/btrfs/extent_map.h

···
 #define BTRFS_EXTENT_MAP_H
 
 #include <linux/compiler_types.h>
-#include <linux/rwlock_types.h>
+#include <linux/spinlock_types.h>
 #include <linux/rbtree.h>
 #include <linux/list.h>
 #include <linux/refcount.h>