dlp_ctrl.c: Adding support for NOP command reception

dlp_ctrl.c: Adding support for NOP command reception

BZ: 33872

This simple patch is adding support for NOP command reception. It is simply
tracing the NOP command reception and dropping it. Nothing else shall be done
in this case.

It is also reverting the patch preventing the ACWAKE to toggle, and hence the
PM to enter low power modes, in the HSI controller driver.

Change-Id: I113bdfce0dd454e41de88308dc704e1ec9257e88
Signed-off-by: Olivier Stoltz Douchet <olivierx.stoltz-douchet@intel.com>
Reviewed-on: http://android.intel.com:8080/46567
Reviewed-by: Roulliere, Pierre <pierre.roulliere@intel.com>
Reviewed-by: Pillet, VincentX <vincentx.pillet@intel.com>
Reviewed-by: Predon, Frederic <frederic.predon@intel.com>
Reviewed-by: Lebsir, SamiX <samix.lebsir@intel.com>
Tested-by: Lebsir, SamiX <samix.lebsir@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>