net: ipa: Annotate struct ipa_power 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 ipa_power.

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

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20230922172858.3822653-8-keescook@chromium.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ipa/ipa_power.c

@@ -67,7 +67,7 @@ struct ipa_power {
 	spinlock_t spinlock;	/* used with STOPPED/STARTED power flags */
 	DECLARE_BITMAP(flags, IPA_POWER_FLAG_COUNT);
 	u32 interconnect_count;
-	struct icc_bulk_data interconnect[];
+	struct icc_bulk_data interconnect[] __counted_by(interconnect_count);
 };
 
 /* Initialize interconnects required for IPA operation */