ice: manage interrupts during poll exit

The driver would occasionally miss that there were outstanding
descriptors to clean when exiting busy/napi poll. This issue has
been in the code since the introduction of the ice driver.

Attempt to "catch" any remaining work by triggering a software
interrupt when exiting napi poll or busy-poll. This will not
cause extra interrupts in the case of normal execution.

This issue was found when running sfnt-pingpong, with busy
poll enabled, and typically with larger I/O sizes like > 8192,
the program would occasionally report > 1 second maximums
to complete a ping pong.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>