ZTS: increase timeout of mmap_sync_001_pos
On load the test needs sometimes a bit more time then just one second.
Doubling the time will help on the QEMU based testings.
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Tino Reichardt <milky-zfs@mcmilk.de>
Closes #16537