mpt3sas: Remove usage of 'struct timeval'

'struct timeval' will have its tv_sec value overflow on 32-bit systems
in year 2038 and beyond. This patch replaces the use of struct timeval
for computing mpi_request.TimeStamp, and instead uses ktime_t which
provides 64-bit seconds value. The timestamp computed remains
unaffected (milliseconds since Unix epoch).

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Acked-by: Sathya Prakash <sathya.prakash@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>