The nfsd4_cb_layout_done() function takes a 'time_t' value,
multiplied by NSEC_PER_SEC*2 to get a nanosecond value.

This works fine on 64-bit architectures, but on 32-bit, any
value over 1 second results in a signed integer overflow
with unexpected results.

Cast one input to a 64-bit type in order to produce the
same result that we have on 64-bit architectures, regarless
of the type of nfsd4_lease.

Fixes: 6b9b2107

 ("nfsd: give up on CB_LAYOUTRECALLs after two lease periods")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>