fsl/fman: use resource_size

Use resource_size rather than a verbose computation on
the end and start fields.

The semantic patch that makes these changes is as follows:
(http://coccinelle.lip6.fr/

)

<smpl>
@@ struct resource ptr; @@
- (ptr.end + 1 - ptr.start)
+ resource_size(&ptr)

@@ struct resource *ptr; @@
- (ptr->end + 1 - ptr->start)
+ resource_size(ptr)
</smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>