xen/unpopulated-alloc: Drop check for virt_addr_valid() in fill_list()

If memremap_pages() succeeds the range is guaranteed to have proper page
table, there is no need for an additional virt_addr_valid() check.

Signed-off-by: Oleksandr Tyshchenko <[e-mail]>
Reviewed-by: Boris Ostrovsky <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Juergen Gross <[e-mail]>

drivers/xen/unpopulated-alloc.c

···
 	for (i = 0; i < alloc_pages; i++) {
 		struct page *pg = virt_to_page(vaddr + PAGE_SIZE * i);
 
-		BUG_ON(!virt_addr_valid(vaddr + PAGE_SIZE * i));
 		pg->zone_device_data = page_list;
 		page_list = pg;
 		list_count++;