net: phy: marvell10g: Force reading of 2.5/5G

As per 802.3bz, if bit 14 of (1.11) "PMA Extended Abilities" indicates
whether or not we should read register (1.21) "2.52/5G PMA Extended
Abilities", which contains information on the support of 2.5GBASET and
5GBASET.

After testing on several variants of PHYS of this family, it appears
that bit 14 in (1.11) isn't always set when it should be.

PHYs 88X3310 (on MacchiatoBin) and 88E2010 do support 2.5G and 5GBASET,
but don't have 1.11.14 set. Their register 1.21 is filled with the
correct values, indicating 2.5G and 5G support.

PHYs 88E2110 do have their 1.11.14 bit set, as it should.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>