scsi: ufs: core: Add debugfs entries for TX Equalization params

scsi: ufs: core: Add debugfs entries for TX Equalization params

Add debugfs support for UFS TX Equalization and UFS TX Equalization
Training (EQTR) to facilitate runtime inspection of link quality. These
entries allow developers to monitor and optimize TX Equalization parameters
and EQTR records during live operation.

The debugfs entries are organized on a per-gear basis under the HBA's
debugfs root. Since TX EQTR is only defined for High Speed Gear 4 (HS-G4)
and above, EQTR-related entries are explicitly excluded for HS-G1 through
HS-G3 to avoid exposing unsupported attributes.

The ufshcd's debugfs folder structure will look like below:

  /sys/kernel/debug/ufshcd/*ufs*/
  |--tx_eq_hs_gear1/
  |  |--device_tx_eq_params
  |  |--host_tx_eq_params
  |--tx_eq_hs_gear2/
  |--tx_eq_hs_gear3/
  |--tx_eq_hs_gear4/
  |--tx_eq_hs_gear5/
  |--tx_eq_hs_gear6/
     |--device_tx_eq_params
     |--device_tx_eqtr_record
     |--host_tx_eq_params
     |--host_tx_eqtr_record

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Can Guo <can.guo@oss.qualcomm.com>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Link: https://patch.msgid.link/20260325152154.1604082-6-can.guo@oss.qualcomm.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>