Replace the use of struct timeval and do_gettimeofday() with
64 bit ktime_get_real_seconds. Prevents 32-bit type overflow
in year 2038 on 32-bit systems.

Driver was using the seconds portion of struct timeval (.tv_secs)
to pass a millseconds timestamp to the firmware. This change maintains
that same behavior using ktime_get_real_seconds.

The structure used to pass the timestamp to firmware is 48 bits and
works fine as long as the top 16 bits are zero and they will be zero
for a long time..ie. thousands of years.

Alternative Change:  Add sub second granularity to timestamp

As noted above, the driver only used the seconds portion of timeval,
ignores the microseconds portion, and by multiplying by 1000 effectively
does a <<10 and always writes zero into timestamp[0].

The alternative change would pass all the bits to the firmware:

        struct timespec64 ts;

        ktime_get_real_ts64(&ts);
        timestamp = ts.tv_sec * MSEC_PER_SEC + ts.tv_nsec / NSEC_PER_MSEC;

Signed-off-by: Alison Schofield <amsfield22@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>