hv_balloon: simplify math in alloc_balloon_pages()

'alloc_unit' in alloc_balloon_pages() is either '512' for 2M allocations or
'1' for 4k allocations. So

1 << get_order(alloc_unit << PAGE_SHIFT)

equals to 'alloc_unit' and the for loop basically sets all them offline.
Simplify the math to improve the readability.

Signed-off-by: Vitaly Kuznetsov <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>

Author: vittyvk

drivers/hv/hv_balloon.c

@@ -1238,7 +1238,7 @@ static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
 			split_page(pg, get_order(alloc_unit << PAGE_SHIFT));
 
 		/* mark all pages offline */
-		for (j = 0; j < (1 << get_order(alloc_unit << PAGE_SHIFT)); j++)
+		for (j = 0; j < alloc_unit; j++)
 			__SetPageOffline(pg + j);
 
 		bl_resp->range_count++;