lib: test_hmm: use min() to improve dmirror_exclusive()

Use min() to simplify the dmirror_exclusive() function and improve its
readability.

Link: https://lkml.kernel.org/r/20240726131245.161695-1-thorsten.blum@toblux.comSigned-off-by: Thorsten Blum <thorsten.blum@toblux.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/test_hmm.c

@@ -799,10 +799,7 @@ static int dmirror_exclusive(struct dmirror *dmirror,
 		unsigned long mapped = 0;
 		int i;
 
-		if (end < addr + (ARRAY_SIZE(pages) << PAGE_SHIFT))
-			next = end;
-		else
-			next = addr + (ARRAY_SIZE(pages) << PAGE_SHIFT);
+		next = min(end, addr + (ARRAY_SIZE(pages) << PAGE_SHIFT));
 
 		ret = make_device_exclusive_range(mm, addr, next, pages, NULL);
 		/*