ARM: dts: am335x: Replace remaining legacy phy_id with phy-handle

Looks like we still have two instances of phy_handle that did not
get update by Grygorii's series. Let's replace these too with
standard phy-handle.

Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Neeraj Dantu <dantuguf14105@gmail.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Koen Kooi <koen@dominion.thruhere.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>