net: keystone_net: move header file from arch to ti-common

The header file for the driver should be in correct place.
So move it to "arch/arm/include/asm/ti-common/keystone_net.h"
and correct driver's external dependencies. At the same time
align and correct some definitions.

Acked-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>