sx8: use real time for the command seconds

Commit 8182503d used monotonic time, but if the adapter is
using the seconds for logging entries, then we'll get duplicate
entries if the system is rebooted. Use real time instead.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 8182503d ("block: sx8.c: Replace timeval with ktime_t")
Signed-off-by: Jens Axboe <axboe@fb.com>