ice: backport XSK queue disable/enable fixes from upstream Linux

[Shivam279Chaudhary]

Backport 4 upstream commits that fix race conditions during AF_XDP/XSK
socket setup/teardown causing false TX watchdog timeouts, NULL pointer
dereferences, and workqueue deadlocks on ice 2.5.4:

• 99099c6bc75a ("ice: reorder disabling IRQ and NAPI in ice_qp_dis")
• 405d9999aa0b ("ice: replace synchronize_rcu with synchronize_net")
• 9da75a511c55 ("ice: toggle netif_carrier when setting up XSK pool")
• 7e3b407ccbea ("ice: remove ICE_CFG_BUSY locking from AF_XDP code")

All fix the original 2d4238f55697 ("ice: Add support for AF_XDP").

Problem

During AF_XDP/XSK socket setup/teardown under TX load, the driver's queue
reconfiguration takes longer than the 5-second watchdog timeout allows. The
kernel incorrectly concludes the NIC has hung and triggers a PF reset. The
reset frees ring pointers while concurrent operations are still accessing
them, causing a NULL pointer dereference followed by a workqueue deadlock.
The NIC never recovers — hosts become permanently unreachable.

Fix

These 4 commits collectively:

1. Reorder NAPI disable before touching queues (closes stale interrupt window)
2. Add synchronize_net() early in teardown (drains in-flight TX)
3. Toggle netif_carrier_off/on (prevents watchdog from firing during reconfig)
4. Remove ICE_CFG_BUSY busy-wait (was never protecting the queue pair)

Backport methodology

Cherry-pick was not possible due to API differences between upstream and
the out-of-tree driver. The combined intent of all four patches was applied
manually, preserving ice-2.5.4-specific code.

Testing

• Intel E810 (PCI 8086:1592), kernel 5.10.252/253
• 64-thread UDP flood (upto ~200 Gbps)
• Without patch: hosts crash within 1-4 XSK lifecycle iterations
• With patch: hosts survive 200+ iterations under sustained load

Related: #58, #61