net: phy: marvell: Support reg config via "marvell, reg-init" DT property

net: phy: marvell: Support reg config via "marvell, reg-init" DT property

This patch adds support for the "marvell,reg-init" DT property, which
is used to describe board specific Marvell PHY register configurations
in the board dts file. This DT property is supported in the Linux Kernel
since a longer time. Adding it to U-Boot now, enables the boards which
describe the register settings in their DT files here as well.

I've included calling this marvell_of_reg_init() to all foo_config()
functions in this patch as well. If CONFIG_DM_ETH is not set, there is
no ofnode, or no "marvell,reg-init" property, the PHY initialization is
unchanged.

The function marvell_of_reg_init() is a port of the Linux version.
Please note that I explicitly did not add error checking and handling
to the U-Boot version, as this is basically not done for phy_read/write
in this Marvell PHY code.

This will be used by the upcoming ethernet support on the MIPS
Octeon EBB 7304 board.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Ramon Fried <rfried.dev@gmail.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>
Cc: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Marek Behún <marek.behun@nic.cz>