iavf: refactor iavf_clean_rx_irq to support legacy and flex descriptors

iavf: refactor iavf_clean_rx_irq to support legacy and flex descriptors

Using VIRTCHNL_VF_OFFLOAD_FLEX_DESC, the iAVF driver is capable of
negotiating to enable the advanced flexible descriptor layout. Add the
flexible NIC layout (RXDID=2) as a member of the Rx descriptor union.

Also add bit position definitions for the status and error indications
that are needed.

The iavf_clean_rx_irq function needs to extract a few fields from the Rx
descriptor, including the size, rx_ptype, and vlan_tag.
Move the extraction to a separate function that decodes the fields into
a structure. This will reduce the burden for handling multiple
descriptor types by keeping the relevant extraction logic in one place.

To support handling an additional descriptor format with minimal code
duplication, refactor Rx checksum handling so that the general logic
is separated from the bit calculations. Introduce an iavf_rx_desc_decoded
structure which holds the relevant bits decoded from the Rx descriptor.
This will enable implementing flexible descriptor handling without
duplicating the general logic twice.

Introduce an iavf_extract_flex_rx_fields, iavf_flex_rx_hash, and
iavf_flex_rx_csum functions which operate on the flexible NIC descriptor
format instead of the legacy 32 byte format. Based on the negotiated
RXDID, select the correct function for processing the Rx descriptors.

With this change, the Rx hot path should be functional when using either
the default legacy 32byte format or when we switch to the flexible NIC
layout.

Modify the Rx hot path to add support for the flexible descriptor
format and add request enabling Rx timestamps for all queues.

As in ice, make sure we bump the checksum level if the hardware detected
a packet type which could have an outer checksum. This is important
because hardware only verifies the inner checksum.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Co-developed-by: Mateusz Polchlopek <mateusz.polchlopek@intel.com>
Signed-off-by: Mateusz Polchlopek <mateusz.polchlopek@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>