hte: Annotate struct hte_device 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 hte_device.

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

Cc: Dipen Patel <dipenp@nvidia.com>
Cc: timestamp@lists.linux.dev
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Dipen Patel <dipenp@nvidia.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Dipen Patel <dipenp@nvidia.com>

drivers/hte/hte.c

@@ -88,7 +88,7 @@ struct hte_device {
 	struct list_head list;
 	struct hte_chip *chip;
 	struct module *owner;
-	struct hte_ts_info ei[];
+	struct hte_ts_info ei[] __counted_by(nlines);
 };
 
 #ifdef CONFIG_DEBUG_FS