net: bcmgenet: reserved phy revisions must be checked first

The reserved gphy_rev value of 0x01ff must be tested before the old
or new scheme for GPHY major versioning are tested, otherwise it will
be treated as 0xff00 according to the old scheme.

Fixes: b04a2f5b

 ("net: bcmgenet: add support for new GENET PHY revision scheme")
Signed-off-by: Doug Berger <opendmb@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>