From: Alex Chapman <alex.chapman@arm.com>

This patch adds the required functionality for the RSS key_update,
RETA, and hash test suites. This includes:
The setting of custom RETA values for routing packets to specific
queues.
The setting of the RSS mode on all ports, to specify how to hash
the packets.
The updating of the RSS hash key used during the hashing process.

Alongside this, there is the addition of a __str__ method to the
RSSOffloadTypesFlags class, so that when flag names are cast to
a string they will use '-' as separators, instead of '_'.
This allows them to be directly used within testpmd RSS commands
without any further changes.

Signed-off-by: Alex Chapman <alex.chapman@arm.com>
Signed-off-by: Thomas Wilks <thomas.wilks@arm.com>

Reviewed-by: Paul Szczepanek <paul.szczepanek@arm.com>
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