API of sensors_get_detected_chips() changed

- NULL was passed to the first parameter of the function to ask for all detected chips as with the old API.

- Old API:

const sensors_chip_name *sensors_get_detected_chips
 (int *nr);

 This function returns all detected chips, one by one. To start at the beginning of the list, use 0 for nr; NULL is returned if we are at the end of the list. Do not try to change these chip names, as they point to internal structures! Do not use nr for anything else.

- New API:

const sensors_chip_name *sensors_get_detected_chips
 (const sensors_chip_name *match, int *nr);

This function returns all detected chips that match a given chip name,
one by one. If no chip name is provided, all detected chips are returned.
To start at the beginning of the list, use 0 for nr; NULL is returned if
we are at the end of the list. Do not try to change these chip names, as
they point to internal structures!