scsi: ufs: mediatek: Avoid sched_clock() misuse

sched_clock() is not meant to be used in portable driver code, and assuming
a particular clock frequency is not how this is meant to be used. It also
causes a build failure because of a missing header inclusion:

drivers/scsi/ufs/ufs-mediatek.c:321:12: error: implicit declaration of function 'sched_clock' [-Werror,-Wimplicit-function-declaration]
        timeout = sched_clock() + retry_ms * 1000000UL;

A better interface to use here ktime_get_mono_fast_ns(), which works mostly
like ktime_get() but is safe to use inside of a suspend callback.

Link: https://lore.kernel.org/r/20211018132022.2281589-1-arnd@kernel.org
Fixes: 9561f58442 ("scsi: ufs: mediatek: Support vops pre suspend to disable auto-hibern8")
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs-mediatek.c

@@ -319,15 +319,15 @@ static void ufs_mtk_wait_idle_state(struct ufs_hba *hba,
 	u32 val, sm;
 	bool wait_idle;
 
-	timeout = sched_clock() + retry_ms * 1000000UL;
-
+	/* cannot use plain ktime_get() in suspend */
+	timeout = ktime_get_mono_fast_ns() + retry_ms * 1000000UL;
 
 	/* wait a specific time after check base */
 	udelay(10);
 	wait_idle = false;
 
 	do {
-		time_checked = sched_clock();
+		time_checked = ktime_get_mono_fast_ns();
 		ufs_mtk_dbg_sel(hba);
 		val = ufshcd_readl(hba, REG_UFS_PROBE);