firmware: exynos-acpm: Count acpm_xfer buffers with __counted_by_ptr

firmware: exynos-acpm: Count acpm_xfer buffers with __counted_by_ptr

Use __counted_by_ptr() attribute on the acpm_xfer buffers so UBSAN will
validate runtime that we do not pass over the buffer size, thus making
code safer.

Usage of __counted_by_ptr() (or actually __counted_by()) requires that
counter is initialized before counted array.

Tested-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Link: https://patch.msgid.link/20260219-firmare-acpm-counted-v2-3-e1f7389237d3@oss.qualcomm.com
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>