net: phy: Add 10BASE-T1L support in phy-c45

This patch is needed because the BASE-T1 uses different registers
for status, control and advertisement to those already
employed in the existing phy-c45 functions.

Where required, genphy_c45 functions will now check whether
the device supports BASE-T1 and use the specific registers
instead: 45.2.7.19 BASE-T1 AN control register,
45.2.7.20 BASE-T1 AN status, 45.2.7.21 BASE-T1 AN
advertisement register, 45.2.7.22 BASE-T1 AN LP Base
Page ability register, 45.2.1.185 BASE-T1 PMA/PMD control
register.

Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Alexandru Tachici <alexandru.tachici@analog.com>
Signed-off-by: David S. Miller <davem@davemloft.net>