[ARM] 4153/1: fix consistent_sync() off-by-one BUG check

In consistent_sync(), start + size can end up pointing one byte
beyond the end of the direct RAM mapping.  We shouldn't BUG() when
this happens.
Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/consistent.c

@@ -485,7 +485,7 @@ void consistent_sync(const void *start, size_t size, int direction)
 {
 	const void *end = start + size;
 
-	BUG_ON(!virt_addr_valid(start) || !virt_addr_valid(end));
+	BUG_ON(!virt_addr_valid(start) || !virt_addr_valid(end - 1));
 
 	switch (direction) {
 	case DMA_FROM_DEVICE:		/* invalidate only */