net: stmmac: reverse Christmas tree notation in stmmac_xpcs_setup

Reorder the variable declarations in descending line length order,
according to the networking coding style.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Wong Vee Khee <vee.khee.wong@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>