net: stmmac: socfpga: convert to devm_stmmac_pltfr_probe()

Convert socfpga to use devm_stmmac_pltfr_probe() to further simplify
the probe function, wrapping the call to the set_phy_mode() method
into socfpga_dwmac_init() which can be called from the plat_dat->init()
method. Also call this from socfpga_dwmac_resume() thereby simplifying
that function.

Using the devm variant also means we can remove the call to
stmmac_pltfr_remove().

Unfortunately, we can't also convert to stmmac_pltfr_pm_ops as there is
extra work done in socfpga_dwmac_resume().

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Tested-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Link: https://patch.msgid.link/E1u5Sns-001IJw-OY@rmk-PC.armlinux.org.uk


Signed-off-by: Jakub Kicinski <kuba@kernel.org>