ice: Remove runtime change of PFINT_OICR_ENA register

Runtime change of PFINT_OICR_ENA register is unnecessary.
The handlers should always clear the atomic bit for each
task as they start, because it will make sure that any late
interrupt will either 1) re-set the bit, or 2) be handled
directly in the "already running" task handler.

Signed-off-by: Md Fahad Iqbal Polash <md.fahad.iqbal.polash@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>