iommu/amd: Ensure GA log notifier callbacks finish running before module unload

iommu/amd: Ensure GA log notifier callbacks finish running before module unload

[ Upstream commit 94c721ea03c7078163f41dbaa101ac721ddac329 ]

Synchronize RCU when unregistering KVM's GA log notifier to ensure all
in-flight interrupt handlers complete before KVM-the module is unloaded.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20250315031048.2374109-1-seanjc@google.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>