net: fman: memac: Convert to devm_of_phy_optional_get()

Use the new devm_of_phy_optional_get() helper instead of open-coding the
same operation.

As devm_of_phy_optional_get() returns NULL if either the PHY cannot be
found, or if support for the PHY framework is not enabled, it is no
longer needed to check for -ENODEV or -ENOSYS.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/f2d801cd73cca36a7162819289480d7fc91fcc7e.1674584626.git.geert+renesas@glider.be


Signed-off-by: Vinod Koul <vkoul@kernel.org>