scsi: ufs: core: Drop last_intr_status/ts stats

In order to prepare introduction of a threaded interrupt handler, drop
last_intr_status & last_intr_ts drop the ufs_stats struct, and the
associated debug code.

Suggested-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250407-topic-ufs-use-threaded-irq-v3-1-08bee980f71e@linaro.org


Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>