examples/l3fwd-power: add Rx interrupt timeout

examples/l3fwd-power: add Rx interrupt timeout

Currently, thread waiting on an interrupt does not have a timeout, so
it will not ever wake up until traffic arrives. This means that, when
time comes to exit the application, it will not quit unless there
happens to be traffic coming in and waking up the thread from sleep.

Fix it so that the interrupt thread sleeps for 10ms before waking up
and attempting to poll again. Additionally, remove the log message
to avoid spamming about entering interrupt mode.

Fixes: 613ce6691c0d ("examples/l3fwd-power: implement proper shutdown")
Cc: stable@dpdk.org
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: David Hunt <david.hunt@intel.com>
Tested-by: Lihong Ma <lihongx.ma@intel.com>