net: sh_eth: Fix PHY state warning splat during system resume

Since commit 744d23c7 ("net: phy: Warn about incorrect
mdio_bus_phy_resume() state"), a warning splat is printed during system
resume with Wake-on-LAN disabled:

	WARNING: CPU: 0 PID: 626 at drivers/net/phy/phy_device.c:323 mdio_bus_phy_resume+0xbc/0xe4

As the Renesas SuperH Ethernet driver already calls phy_{stop,start}()
in its suspend/resume callbacks, it is sufficient to just mark the MAC
responsible for managing the power state of the PHY.

Fixes: fba863b8 ("net: phy: make PHY PM ops a no-op if MAC driver manages PHY PM")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/c6e1331b9bef61225fa4c09db3ba3e2e7214ba2d.1663598886.git.geert+renesas@glider.be


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