regulator: da9062: Annotate struct da9062_regulators 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 da9062_regulators.

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

Cc: Support Opensource <support.opensource@diasemi.com>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Link: https://lore.kernel.org/r/20230922175330.work.066-kees@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: kees

drivers/regulator/da9062-regulator.c

@@ -73,7 +73,7 @@ struct da9062_regulators {
 	int					irq_ldo_lim;
 	unsigned				n_regulators;
 	/* Array size to be defined during init. Keep at end. */
-	struct da9062_regulator			regulator[];
+	struct da9062_regulator			regulator[] __counted_by(n_regulators);
 };
 
 /* Regulator operations */