drivers: net: cpsw: remove platform data header file of cpsw

CPSW driver no longer supports platform register as all the SoCs which has CPSW
are supporting DT only booting, so moving cpsw.h header file from platform
include to drivers/net/ethernet/ti

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>