net: sun8i_emac: Test the correct phy

H3/H5 can either use the internal phy or an external one.
Before getting clock and resets for the internal phy,
test that we are using it because otherwise it break emac
when using an external phy.

Tested-on: OrangePi PC2 (H5)
Fixes: 2348453c (net: sun8i_emac: Add EPHY CLK and RESET support)
Signed-off-by: Emmanuel Vadot <manu@freebsd.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>