input: sensor: add support high resolution polling delay for akm09911

The polling delay of akm09911 is not accurate since it uses the
system_wq to queue the delayed work. This may cause the work unable
to be scheduled in time.  So add a dedicated workqueue and improve
the priority. Also use hrtimer to improve the timer resolution.

Change-Id: I3aacd763ab6221fd158ad02c3c99ad5ca7d3de7c
Signed-off-by: Oliver Wang <mengmeng@codeaurora.org>