IB/hfi1: Clean up type used and casting

In all other places in this file where 'find_first_bit' is called,
port_num is defined as a 'u8' and no casting is done.

Do the same here in order to be more consistent.
Signed-off-by: NChristophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: NDoug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/mad.c

@@ -2604,7 +2604,7 @@ static int pma_get_opa_datacounters(struct opa_pma_mad *pmp,
 	u8 lq, num_vls;
 	u8 res_lli, res_ler;
 	u64 port_mask;
-	unsigned long port_num;
+	u8 port_num;
 	unsigned long vl;
 	u32 vl_select_mask;
 	int vfi;
@@ -2640,7 +2640,7 @@ static int pma_get_opa_datacounters(struct opa_pma_mad *pmp,
 	port_num = find_first_bit((unsigned long *)&port_mask,
 				  sizeof(port_mask));
 
-	if ((u8)port_num != port) {
+	if (port_num != port) {
 		pmp->mad_hdr.status |= IB_SMP_INVALID_FIELD;
 		return reply((struct ib_mad_hdr *)pmp);
 	}