net: emac: emac gigabit ethernet controller driver

Add support for the Qualcomm Technologies, Inc. EMAC gigabit Ethernet
controller.

This driver supports the following features:
1) Checksum offload.
2) Interrupt coalescing support.
3) SGMII phy.
4) phylib interface for external phy

Based on original work by
	Niranjana Vishwanathapura <nvishwan@codeaurora.org>
	Gilad Avidov <gavidov@codeaurora.org>

Signed-off-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>