ARM: dts: dra72-evm-revc: enable irqs for dp83867 eth phys

TI DRA72-EVM Rev C has two DP83867 ethernet phys which support IRQ
generation in case of phy/link status changes. The INT/PWDN lines from both
DP83867 phys are wired to DRA7 gpio6.16, so reflect the same in DT.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>