drivers/net/smsc911x.c: Fix resource size off by 1 error

The call resource_size(res) returns res->end - res->start + 1 and thus the
second change is semantics-preserving.  res_size is then used as the second
argument of a call to request_mem_region, and the memory allocated by this
call appears to be the same as what is released in the two calls to
release_mem_region.  So the size argument for those calls should be
resource_size(size) as well.  Alternatively, in the second call to
release_mem_region, the second argument could be res_size, as that variable
has already been initialized at the point of this call.

The problem was found using the following semantic patch:
(http://www.emn.fr/x-info/coccinelle/)

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

- (res->end - res->start) + 1
+ resource_size(res)

@@
struct resource *res;
@@

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

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>