hwmon: (mc13783-adc) Increase size of name string

smatch complains about

mc13783_adc_probe() error: snprintf() chops off the last chars of
'id->name': 20 +vs 10

Use PLATFORM_NAME_SIZE instead of '10' as size when declaring
the name variable.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>