Fixup wrong types for dprint()

Signed-off-by: Jens Axboe <axboe@kernel.dk>
gettime: use 32-bit atomic sequences

Not all platforms have 64-bit wide atomic sync_and_fetch(). If
we just check for overflow, it should be OK to use a 32-bit
sequence number.

Signed-off-by: Jens Axboe <axboe@kernel.dk>