It adds the helper function of_get_phy_mode getting phy interface
from device tree.
Signed-off-by: NShawn Guo <shawn.guo@linaro.org>
Cc: Grant Likely <grant.likely@secretlab.ca>
Acked-by: NGrant Likely <grant.likely@secretlab.ca>
Acked-by: NDavid Miller <davem@davemloft.net>