dedup, uffd: remove -1 handling for seep_pagemap_page return value

The return value of seep_pagemap_page can be either 1 (page found) or 0 (no
page found). There's no point in checking its return value for -1.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Pavel Emelyanov <xemul@virtuozzo.com>

criu/pagemap.c

@@ -97,10 +97,8 @@ int dedup_one_iovec(struct page_read *pr, struct iovec *iov)
 		struct page_read * prp;
 
 		ret = pr->seek_page(pr, off);
-		if (ret == -1)
-			return -1;
-
 		if (ret == 0) {
+			pr_warn("Missing %lx in parent pagemap\n", off);
 			if (off < pr->cvaddr && pr->cvaddr < iov_end)
 				off = pr->cvaddr;
 			else