As explained in PR 277038, iflib calls IFDI_DETACH() and then
IFDI_QUEUES_FREE(). With igc, the latter writes to a register after it
has been unmapped.
igc_if_detach() already calls igc_release_hw_control(), and looking at
callers of igc_if_queues_free(), that appears to be sufficient. So,
just remove the igc_release_hw_control() call.
PR: 277038
Diagnosed by: Mike Belanger <mibelanger@qnx.com>