i2c: Use resource_size

Use the function resource_size, which reduces the chance of introducing
off-by-one errors in calculating the resource size.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
struct resource *res;
@@

- (res->end - res->start) + 1
+ resource_size(res)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/drivers/i2c/busses/i2c-simtec.c b/drivers/i2c/busses/i2c-simtec.c
index 042fda2..6407f47 100644
--- a/drivers/i2c/busses/i2c-simtec.c
+++ b/drivers/i2c/busses/i2c-simtec.c
@@ -92,7 +92,7 @@
 		goto err;
 	}
 
-	size = (res->end-res->start)+1;
+	size = resource_size(res);
 
 	pd->ioarea = request_mem_region(res->start, size, dev->name);
 	if (pd->ioarea == NULL) {