scsi: mpt3sas: Add support for 22.5 Gbps SAS link rate

Add handling for MPI26_SAS_NEG_LINK_RATE_22_5 in
_transport_convert_phy_link_rate(). This maps the new 22.5 Gbps
negotiated rate to SAS_LINK_RATE_22_5_GBPS, to get correct PHY link
speeds.

Signed-off-by: Ranjan Kumar <ranjan.kumar@broadcom.com>
Message-Id: <20250922095113.281484-4-ranjan.kumar@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>