This patch introduces adapter->task_requests register responsible for
recording requests for mod_task, msf_task, mbx_task, fdir_task and
phy_task calls. Instead of enqueueing these tasks with
GROUPTASK_ENQUEUE, handlers will be called directly from
ixgbe_if_update_admin_status() while holding ctx lock.

SIOCGIFXMEDIA ioctl() call reads adapter->media list. The list is
deleted and rewritten in ixgbe_handle_msf() task without holding ctx
lock. This change is needed to maintain data coherency when sharing
adapter info via ioctl() calls.

Patch co-authored by Krzysztof Galazka <krzysztof.galazka@intel.com>.