octeontx2-af: cn10k: Add RPM MAC support

OcteonTx2's next gen platform the CN10K has RPM MAC which has a
different serdes when compared to CGX MAC. Though the underlying
HW is different, the CSR interface has been designed largely inline
with CGX MAC, with few exceptions though. So we are using the same
CGX driver for RPM MAC as well and will have a different set of APIs
for RPM where ever necessary.

This patch adds initial support for CN10K's RPM MAC i.e. the driver
registration, communication with firmware etc. For communication with
firmware, RPM provides a different IRQ when compared to CGX.
The CGX and RPM blocks support different features. Currently few
features like ptp, flowcontrol and higig are not supported by RPM. This
patch adds new mailbox message "CGX_FEATURES_GET" to get the list of
features supported by underlying MAC.

RPM has different implementations for RX/TX stats. Unlike CGX,
bar offset of stat registers are different. This patch adds
support to access the same and dump the values in debugfs.

Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>