dt-bindings: hwmon: ti,tmp421: Fix type for 'ti,n-factor'

'ti,n-factor' is read as a 32-bit signed value, so the type and constraints
are wrong. The same property is also defined for ti,tmp464 and is correct.

The constraints should also not be under 'items' as this property is not an
array.

Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Krzysztof Kozlowski <krzk+dt@kernel.org>
Cc: linux-hwmon@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220413134729.3112190-1-robh@kernel.org
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

dt-bindings: hwmon: allow specifying channels for tmp421

Add binding description for the per temperature channel configuration
like labels and n-factor.

Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/d1721a50efc0f88728614b5b07c0d9332ae4971c.1634206677.git.krzysztof.adamski@nokia.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

dt-bindings: hwmon: add missing tmp421 binding

Add basic description of the tmp421 driver DT bindings.

Signed-off-by: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/84ac871e30a406a1613d140a084b4f3390753099.1634206677.git.krzysztof.adamski@nokia.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>