IB/mlx5: Add mutex destroy call to cap_mask_mutex mutex

mutex_destroy() call for device's cap_mask_mutex mutex is missing, let's
add it to annotate destruction.

Fixes: e126ba97 ("mlx5: Add driver for Mellanox Connect-IB adapters")
Link: https://lore.kernel.org/r/20210113121703.559778-4-leon@kernel.org


Signed-off-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>