powerpc: Fix "unused variable" warning in pci_dlpar.c

This gets rid of this build warning:

arch/powerpc/platforms/pseries/pci_dlpar.c: In function 'init_phb_dynamic':
arch/powerpc/platforms/pseries/pci_dlpar.c:192: warning: unused variable 'b'

This is one of the very few warnings left in a ppc64_defconfig build and
getting rid of it will make it easier to see future introduced ones (in
fact this was introduced very recently).
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/pseries/pci_dlpar.c

@@ -189,7 +189,6 @@ struct pci_controller * __devinit init_phb_dynamic(struct device_node *dn)
 {
 	struct pci_controller *phb;
 	int primary;
-	struct pci_bus *b;
 
 	primary = list_empty(&hose_list);
 	phb = pcibios_alloc_controller(dn);