test/hotplug: increase the test time for hotplug

This will make sure the hotplug instance not exit before all the hot insert and
remove events done, the setup.sh for hot insert events will use several seconds
sometimes.

Change-Id: I4ad61937760529547cdcf7701f3c3d9033121e45
Signed-off-by: Cunyin Chang <cunyin.chang@intel.com>
Reviewed-on: https://review.gerrithub.io/362131


Tested-by:  <sys_sgsw@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>