cxgb4: Annotate struct cxgb4_tc_u32_table 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 checking 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 cxgb4_tc_u32_table.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Raju Rangoju <rajur@chelsio.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230929181149.3006432-3-keescook@chromium.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/chelsio/cxgb4/cxgb4_tc_u32_parse.h

@@ -331,6 +331,6 @@ struct cxgb4_link {
 
 struct cxgb4_tc_u32_table {
 	unsigned int size;          /* number of entries in table */
-	struct cxgb4_link table[]; /* Jump table */
+	struct cxgb4_link table[] __counted_by(size); /* Jump table */
 };
 #endif /* __CXGB4_TC_U32_PARSE_H */