RDMA/irdma: Annotate flexible array with __counted_by() in struct irdma_qvlist_info

RDMA/irdma: Annotate flexible array with __counted_by() in struct irdma_qvlist_info

'num_vectors' is used to count the number of elements in the 'qv_info'
flexible array in "struct irdma_qvlist_info".

So annotate it with __counted_by() to make it explicit and enable some
additional checks.

This allocation is done in irdma_save_msix_info().

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/2ca8b14adf79c4795d7aa95bbfc79253a6bfed82.1716102112.git.christophe.jaillet@wanadoo.fr
Acked-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>