hwmon: (coretemp) Fix truncated name of alarm attributes

commit 3f9aec7610b39521c7c69d754de7265f6994c194 upstream.

When the core number exceeds 9, the size of the buffer storing the
alarm attribute name is insufficient and the attribute name is
truncated. This causes libsensors to skip these attributes as the
truncated name is not recognized.

Reported-by: Andreas Hollmann <hollmann@in.tum.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>