iavf: add a common function for undoing the interrupt scheme

iavf: add a common function for undoing the interrupt scheme

Add a new function iavf_free_interrupt_scheme that does the inverse of
iavf_init_interrupt_scheme. Symmetry is nice. And there will be three
callers already.

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Reviewed-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/r/20231027175941.1340255-8-jacob.e.keller@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>