staging: fsl-dpaa2: ethsw: Remove unused port_priv variable

After 1b8b589d ("staging: fsl-dpaa2: ethsw: Remove getting
PORT_BRIDGE_FLAGS") we are not accessing any driver private data
anymore, remove port_priv which is unused.

Fixes: 1b8b589d

 ("staging: fsl-dpaa2: ethsw: Remove getting PORT_BRIDGE_FLAGS")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>