net: stmmac: Add driver for Qualcomm ethqos

Add glue driver to support Qualcomm ETHQOS using stmmac driver.

This is based on downstream driver written by Siddarth Gupta, Sunil
Kumar Paidimarri, Rahul Ankushrao Kawadgave, Nisha Menon, Jagadeesh
Babu Challagundla, Chaitanya Pratapa, Lakshit Tyagi, Suraj Jaiswal,
Sneh Shah and Ventrapragada Ravi Kanth

Co-developed-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>