lib: maple_tree: remove unneeded initialization in mtree_range_walk()

Before the do-while loop in mtree_range_walk(), the variables next, min,
max need to be initialized.  The variables last, prev_min and prev_max are
set within the loop body before they are eventually used after exiting the
loop body.

As it is a do-while loop, the loop body is executed at least once, so the
variables last, prev_min and prev_max do not need to be initialized before
the loop body.

Remove unneeded initialization of last and prev_min.

The needless initialization was reported by clang-analyzer as Dead Stores.

As the compiler already identifies these assignments as unneeded, it
optimizes the assignments away.  Hence:

No functional change. No change in object code.

Link: https://lkml.kernel.org/r/20221026120029.12555-2-lukas.bulwahn@gmail.com
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/maple_tree.c

@@ -2903,8 +2903,8 @@ static inline void *mtree_range_walk(struct ma_state *mas)
 	unsigned long max, min;
 	unsigned long prev_max, prev_min;
 
-	last = next = mas->node;
-	prev_min = min = mas->min;
+	next = mas->node;
+	min = mas->min;
 	max = mas->max;
 	do {
 		offset = 0;