IB/core: Annotate umem_mutex acquisition under fs_reclaim for lockdep

Following the fix in the previous commit ("IB/mlx5: Fix potential
deadlock in MR deregistration"), teach lockdep explicitly about the
locking order between fs_reclaim and umem_mutex.

The previous commit resolved a potential deadlock scenario where
kzalloc(GFP_KERNEL) was called while holding umem_mutex, which could
lead to reclaim and eventually invoke the MMU notifier
(mlx5_ib_invalidate_range()), causing a recursive acquisition of
umem_mutex.

To prevent such issues from reoccurring unnoticed in future code
changes, add a lockdep annotation in ib_init_umem_odp() that simulates
taking umem_mutex inside a reclaim context. This makes lockdep aware
of this locking dependency and ensures that future violations—such as
calling kzalloc() or any memory allocator that may enter reclaim while
holding umem_mutex—will immediately raise a lockdep warning.

Signed-off-by: Or Har-Toov <ohartoov@nvidia.com>
Reviewed-by: Michael Guralnik <michaelgur@nvidia.com>
Link: https://patch.msgid.link/9d31b9d8fe1db648a9f47cec3df6b8463319dee5.1750061698.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>

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