hwmon: (coretemp) remove struct platform_data * parameter from create_core_data()

The only caller of the function obtained the pointer solely for the
purpose of passing it to this function, while it can be easily
determined from the struct platform_device * parameter also passed.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>