net: phy: marvell10g: report if the PHY fails to boot firmware

Some boards do not have the PHY firmware programmed in the 3310's flash,
which leads to the PHY not working as expected.  Warn the user when the
PHY fails to boot the firmware and refuse to initialise.

Fixes: 20b2af32

 ("net: phy: add Marvell Alaska X 88X3310 10Gigabit PHY support")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>