TI DaVinci EMAC: Add suspend/resume capability

Add suspend/resume capability to TI DaVinci EMAC driver.

Signed-off-by: Ranjith Lohithakshan <ranjithl@ti.com>
Signed-off-by: Chaithrika U S <chaithrika@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>