iio:ad7793: Fix ad7785 product ID

commit 785171fd6cd7dcd7ada5a733b6a2d44ec566c3a0 upstream.

While the datasheet for the AD7785 lists 0xXB as the product ID the actual
product ID is 0xX3.

Fix the product ID otherwise the driver will reject the device due to non
matching IDs.

Fixes: e786cc26 ("staging:iio:ad7793: Implement stricter id checking")
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>