md/md-bitmap: remove md_bitmap_setallbits()

md_bitmap_setallbits() is not used, hence can be removed.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240826074452.1490072-21-yukuai1@huaweicloud.comSigned-off-by: Song Liu <song@kernel.org>

drivers/md/md-bitmap.h

@@ -261,7 +261,6 @@ void mddev_set_bitmap_ops(struct mddev *mddev);
 
 /* these are used only by md/bitmap */
 
-int  md_bitmap_setallbits(struct bitmap *bitmap);
 void md_bitmap_write_all(struct bitmap *bitmap);
 
 void md_bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);