net: stmmac: check fwnode for phy device before scanning for phy

Some DT devices already have phy device configured in the DT/ACPI.
Current implementation scans for a phy unconditionally even though
there is a phy listed in the DT/ACPI and already attached.

We should check the fwnode if there is any phy device listed in
fwnode and decide whether to scan for a phy to attach to.

Fixes: fe2cfbc9

 ("net: stmmac: check if MAC needs to attach to a PHY")
Reported-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/lkml/20230403212434.296975-1-martin.blumenstingl@googlemail.com/


Tested-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Shahab Vahedi <shahab@synopsys.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Suggested-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Michael Sit Wei Hong <michael.wei.hong.sit@intel.com>
Link: https://lore.kernel.org/r/20230406024541.3556305-1-michael.wei.hong.sit@intel.com


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