msm: ipa: stay in NAPI mode when default pipe has low credits

When we have no buffer available in HW and switch to irq, a dead-loop is
observed between sending force close comamnd and replenish workqueue.
The fix is to keep in polling mode, wait for napi-poll and replenish again.

Change-Id: Ied0504564f86f41b8b5f9aa25170768027bf3391
Signed-off-by: Ashok Vuyyuru <avuyyuru@codeaurora.org>
Signed-off-by: Bojun Pan <bojunp@codeaurora.org>