FROMGIT: scsi: ufs: ufs-qcom: Factor out the logic finding the HS Gear

In the preparation of adding support for new gears, move the logic that
finds the gear for each platform to a new function. This helps with code
readability and also allows the logic to be used in other places of the
driver in future.

While at it, make it clear that this driver only supports symmetric gear
setting (hs_tx_gear == hs_rx_gear).

Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # Qdrive3/sa8540p-ride
Change-Id: I84a9ba276db78e041bc9913e1d6554e05da4023b
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Bug: 267974767
(cherry picked from commit c2709865 git://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git

 for-next)
Signed-off-by: Bart Van Assche <bvanassche@google.com>