octeontx2-pf: PFC config support with DCBx

octeontx2-pf: PFC config support with DCBx

Data centric bridging designed to eliminate packet loss due to
queue overflow by adding enhancements to ethernet network such as
proprity flow control etc. This patch adds support for management
of Priority flow control(PFC) on Octeontx2 and CN10K interfaces.

To enable PFC for all priorities
	dcb pfc set dev eth0 prio-pfc all:on/off

To enable PFC on selected priorites
	dcb pfc set dev eth0 prio-pfc 0:on/off 1:on/off ..7:on/off

With the ntuple commands user can map Priority to receive queues.
On queue overflow NIX will assert backpressure such that PFC pause frames
are genarated with mapped priority.

To map priority 7 to Queue 1
ethtool -U eth0 flow-type ether dst xx:xx:xx:xx:xx:xx vlan 0xe00a
m 0x1fff  queue 1

Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>