i40e: Annotate struct i40e_qvlist_info with __counted_by

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct i40e_qvlist_info.

Cc: Tony Nguyen <anthony.l.nguyen@intel.com>
Cc: Shiraz Saleem <shiraz.saleem@intel.com>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Gurucharan G <gurucharanx.g@intel.com>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

 [1]
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20231003231838.work.510-kees@kernel.org


Signed-off-by: Kees Cook <keescook@chromium.org>