driver: net: ldpaa: Add debug information

Add following debug information in the driver
 - Get various DPNI counter values
 - Get link status of DPNI objects
 - Get information of both ends of connection (DPMAC - DPNI)

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>