enetc: Add RFS and RSS support

A ternary match table is used for RFS. If multiple entries in the table
match, the entry with the lowest numerical values index is chosen as the
matching entry.  Entries in the table are identified using an index
which takes a value from 0 to PRFSCAPR[NUM_RFS]-1 when accessed by the
PSI (PF).
Portions of the RFS table can be assigned to each SI by the PSI (PF)
driver in PSIaRFSCFGR.  Assignments are cumulative, the entries assigned
to SIn start after those assigned to SIn-1.  The total assignments to
all SIs must be equal to or less than the number available to the port
as found in PRFSCAPR.

For RSS, the Toeplitz hash function used requires two inputs, a 40B
random secret key that is supplied through the PRSSKR0-9 registers as well
as the relevant pieces of the packet header (n-tuple).  The 6 LSB bits of
the hash function result will then be used as a pointer to obtain the tag
referenced in the 64 entry indirection table.  The result will provide a
winning group which will be used to help route the received packet.

Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Signed-off-by: Claudiu Manoil <claudiu.manoil@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>