staging/lustre: use 64-bit computation in s2dhms()

The s2dhms computes the day/hour/minute/second values from a time_t,
which stops working in 2038. This changes the code to take a time64_t
argument, and use div_u64_rem() to implement the first division.

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>