scsi: ufs: core: Improve IOPS

scsi: ufs: core: Improve IOPS

Measurements have shown that IOPS improve by 2% - 3% on my UFS 4 test
setup every time a ktime_get() call is removed from the UFS driver
command processing path. Hence this patch that modifies
ufshcd_clk_scaling_start_busy() such that ktime_get() is only called if
the returned value will be used.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20250813171049.3399387-1-bvanassche@acm.org
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>