staging/lustre: use 64-bit timestamps for mdc

These three are timestamps that are sent over the wire in mdc_lib
and the obd logging 64-bit values, but are generated using the 32-bit
get_seconds() function, which will eventually overflow.

Changing them to use 64-bit ktime_get_real_seconds() solves the problem.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>