net: stmmac: Fix ethool link settings ops for integrated PCS

Currently get/set_link_ksettings ethtool ops are dependent on PCS.
When PCS is integrated, it will not have separate link config.
Bypass configuring and checking PCS for integrated PCS.

Fixes: aa571b62

 ("net: stmmac: add new switch to struct plat_stmmacenet_data")
Tested-by: Andrew Halaney <ahalaney@redhat.com> # sa8775p-ride
Signed-off-by: Sneh Shah <quic_snehshah@quicinc.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>