i40e: remove un-necessary io-write

Driver needs to clean PBA only when interrupts are turned off and we
are polling instead.

Change-Id: Ic0c1da761bd3abe7f73b1cc8bcddf8e3a232fd0f
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>