w1: ds2438: changed sysfs macro for rw file

The iad sysfs file has permissions for read and write. Changed to the
recommended macro BIN_ATTR_RW.

Signed-off-by: Luiz Sampaio <sampaio.ime@gmail.com>
Link: https://lore.kernel.org/r/20210519223046.13798-4-sampaio.ime@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>