net: dsa: qca8k: Add define for port VID

Rather than using a magic value of 1 when configuring the port VIDs add
a QCA8K_PORT_VID_DEF define and use that instead. Also fix up the
bitmask in the process; the top 4 bits are reserved so this wasn't a
problem, but only masking 12 bits is the correct approach.

Signed-off-by: Jonathan McDowell <noodles@earth.li>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/dsa/qca8k.h b/drivers/net/dsa/qca8k.h
index 3143939..92216a5 100644
--- a/drivers/net/dsa/qca8k.h
+++ b/drivers/net/dsa/qca8k.h
@@ -22,6 +22,8 @@
 
 #define QCA8K_CPU_PORT					0
 
+#define QCA8K_PORT_VID_DEF				1
+
 /* Global control registers */
 #define QCA8K_REG_MASK_CTRL				0x000
 #define   QCA8K_MASK_CTRL_ID_M				0xff