iio: acpi: Improve iio_read_acpi_mount_matrix()

iio: acpi: Improve iio_read_acpi_mount_matrix()

By using ACPI_HANDLE() the handler argument can be retrieved directly.
Replace ACPI_COMPANION() + dereference with ACPI_HANDLE().

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20241024191200.229894-5-andriy.shevchenko@linux.intel.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>