linux-phytec-ti

net: netcp: ethss: add support of subsystem register region regmap

10gbe phy driver needs to access the 10gbe subsystem control
register during phy initialization. To facilitate the shared
access of the subsystem register region between the 10gbe Ethernet
driver and the phy driver, this patch adds support of the
subsystem register region defined by a syscon node in the dts.

Although there is no shared access to the gbe subsystem register
region, using syscon for that is for the sake of consistency.

This change is backward compatible with previously released gbe
devicetree bindings.

Signed-off-by: WingMan Kwok <w-kwok2@ti.com>
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>