ARM: dts: dra7: Add CPSW and MDIO module nodes for dra7

Add CPSW and MDIO related device tree data for DRA7XX and made as status
disabled. Phy-id, pinmux for active and sleep state needs to be added in
board dts files and enable the CPSW device.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>