null_blk: null_alloc_page() cleanup

Remove goto labels and use direct returns as error unwinding code only
needs to free t_page variable if we alloc_pages() call fails as having
two labels for one kfree() can be avoided easily.
Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220222152852.26043-3-kch@nvidia.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/null_blk/main.c

@@ -783,18 +783,16 @@ static struct nullb_page *null_alloc_page(void)
 
 	t_page = kmalloc(sizeof(struct nullb_page), GFP_NOIO);
 	if (!t_page)
-		goto out;
+		return NULL;
 
 	t_page->page = alloc_pages(GFP_NOIO, 0);
-	if (!t_page->page)
-		goto out_freepage;
+	if (!t_page->page) {
+		kfree(t_page);
+		return NULL;
+	}
 
 	memset(t_page->bitmap, 0, sizeof(t_page->bitmap));
 	return t_page;
-out_freepage:
-	kfree(t_page);
-out:
-	return NULL;
 }
 
 static void null_free_page(struct nullb_page *t_page)