hw/sensor/tmp105: Use registerfields API

To improve readability, use the registerfields API.
Define the register bits with FIELD(), and use the
FIELD_EX8() and FIELD_DP8() macros. Remove the
abbreviations in comments.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Message-Id: <20240906154911.86803-3-philmd@linaro.org>