qemu/tests/cfg/timedrift_adjust_time.cfg: Fix config typo

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
qemu/tests/cfg/timedrift_adjust_time.cfg: Increase inactivity treshold to 3600

This test will stop VMs for 1800 seconds, which will
trigger the inactivity watcher treshold, and print
messages such as:

    virt-tests-vm1 screen is inactive for more than 1802 s (30 min)

In this case the message is harmless, and more often than
not, will confuse users. Increase the inactivity treshold
for this particular test.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #208 from autotest/timedrift_adjust_time_fixes

Timedrift adjust time fixes