staging: exfat: stop using 32-bit time_t

time_t suffers from overflow problems and should not be used.

In exfat, it is currently used in two open-coded time64_to_tm()
implementations. Changes those to use the existing function instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20190906150917.1025250-2-arnd@arndb.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>