After discussing with Amlogic, the Synopsys GMAC version used by
the gx and axg family is the 3.70a. Set this is in DT
Signed-off-by: NJerome Brunet <jbrunet@baylibre.com>
Reviewed-by: NMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: NKevin Hilman <khilman@baylibre.com>