radix tree: remove unused variable

Recent versions of clang warn about an unused variable, though older
versions saw the 'slot++' as a use and did not warn:

radix-tree.c:1136:50: error: parameter 'slot' set but not used [-Werror,-Wunused-but-set-parameter]

It's clearly not needed any more, so just remove it.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 3a08cd5 ("radix tree: Remove multiorder support")
Signed-off-by: Arnd Bergmann <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Peng Zhang <[email protected]>
Cc: Rong Tao <[email protected]>
Cc: Tom Rix <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

lib/radix-tree.c

@@ -1136,7 +1136,6 @@ static void set_iter_tags(struct radix_tree_iter *iter,
 void __rcu **radix_tree_iter_resume(void __rcu **slot,
 					struct radix_tree_iter *iter)
 {
-	slot++;
 	iter->index = __radix_tree_iter_add(iter, 1);
 	iter->next_index = iter->index;
 	iter->tags = 0;