input: qcom-hv-haptics: update FIFO samples in IRQ thread

Instead of sending a completion from the IRQ thread to notify a
worker thread to update the FIFO samples, update the samples in
the IRQ thread directly. This should help achieve lower latency
which is good for FIFO playing.

Meanwhile, following changes are made for FIFO playing:
 1) Defer stopping command into erase() function if it's coming
    before all FIFO samples are played. This gives the hardware
    a little more time to play before stopping.
 2) Restore FIFO play rate to T_LRA after playing is done according
    to hardware recommendation.

Change-Id: I7b21589641d753d45b1261ce0e342373c249f4e5
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>