dpaa2-eth: Add flow steering support without masking

On platforms that lack a TCAM (like LS1088A), masking of
flow steering keys is not supported. Until now we didn't
offer flow steering capabilities at all on these platforms,
since our driver implementation configured a "comprehensive"
FS key (containing all supported header fields), with masks
used to ignore the fields not present in the rules provided
by the user.

We now allow ethtool rules that share a common key (i.e. have
the same header fields). The FS key is now kept in the driver
private data and initialized when the first rule is added to
an empty table, rather than at probe time. If a rule with a new
composition key is wanted, the user must first manually delete
all previous rules.

When building a FS table entry to pass to firmware, we still use
the old building algorithm, which assumes an all-supported-fields
key, and later collapse the fields which aren't actually needed.

Masked rules are not supported; if provided, the mask value
will be ignored. For firmware versions older than MC10.7.0
(that only offer the legacy ABIs for configuring distribution
keys) flow steering without masking support remains unavailable.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>