powerpc/powernv: 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 - ptr.start + 1)
+ resource_size(&ptr)
</smpl>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1577900990-8588-11-git-send-email-Julia.Lawall@inria.fr

arch/powerpc/platforms/powernv/pci-ioda.c

@@ -792,7 +792,7 @@ static int pnv_ioda_deconfigure_pe(struct pnv_phb *phb, struct pnv_ioda_pe *pe)
 		fcomp = OPAL_IGNORE_RID_FUNCTION_NUMBER;
 		parent = pe->pbus->self;
 		if (pe->flags & PNV_IODA_PE_BUS_ALL)
-			count = pe->pbus->busn_res.end - pe->pbus->busn_res.start + 1;
+			count = resource_size(&pe->pbus->busn_res);
 		else
 			count = 1;
 
@@ -874,7 +874,7 @@ static int pnv_ioda_configure_pe(struct pnv_phb *phb, struct pnv_ioda_pe *pe)
 		fcomp = OPAL_IGNORE_RID_FUNCTION_NUMBER;
 		parent = pe->pbus->self;
 		if (pe->flags & PNV_IODA_PE_BUS_ALL)
-			count = pe->pbus->busn_res.end - pe->pbus->busn_res.start + 1;
+			count = resource_size(&pe->pbus->busn_res);
 		else
 			count = 1;