dsa: Rename switch chip data to cd

The dsa_switch structure contains a dsa_chip_data member called pd.
However in the rest of the code, pd is used for dsa_platform_data.
This is confusing. Rename it cd, which is already often used in dsa.c
and slave.c for this data type.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/mv88e6xxx.c b/drivers/net/dsa/mv88e6xxx.c
index 8659cba..ee78309 100644
--- a/drivers/net/dsa/mv88e6xxx.c
+++ b/drivers/net/dsa/mv88e6xxx.c
@@ -3023,9 +3023,9 @@
 	for (i = 0; i < 32; i++) {
 		int nexthop = 0x1f;
 
-		if (ps->ds->pd->rtable &&
+		if (ps->ds->cd->rtable &&
 		    i != ps->ds->index && i < ps->ds->dst->pd->nr_chips)
-			nexthop = ps->ds->pd->rtable[i] & 0x1f;
+			nexthop = ps->ds->cd->rtable[i] & 0x1f;
 
 		err = _mv88e6xxx_reg_write(
 			ps, REG_GLOBAL2,