SolutionEngine7724: fix typo in Ether platform data

Commit bd61224b (SolutionEngine7724: fix Ether
support) has a typo in the 'phy_interface' field name of the platform data which
causes build error -- fix it.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>