uboot-imx

phy: Fix warning due to missing definition of structure

Fix this sort of warning if generic-phy.h is included:

include/generic-phy.h:52:42: warning: ‘struct ofnode_phandle_args’ declared inside parameter list will not be visible outside of this definition or declaration
  int (*of_xlate)(struct phy *phy, struct ofnode_phandle_args *args);

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>