scsi: ufs: host: mediatek: Remove duplicate function

scsi: ufs: host: mediatek: Remove duplicate function

Remove the duplicate ufs_mtk_us_to_ahit() function in the UFS Mediatek
driver and export the existing ufshcd_us_to_ahit() function for shared
use. This change reduces redundancy and maintains consistency across the
codebase.

Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Acked-by: Chun-Hung Wu <chun-hung.wu@mediatek.com>
Link: https://patch.msgid.link/20250924094527.2992256-7-peter.wang@mediatek.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>