hwmon: (coretemp) Drop duplicate function get_pkg_tjmax
Function get_pkg_tjmax is a simplified copy of get_tjmax. Drop it and
always use get_tjmax, result is the same and this avoids code
duplication.
Also make get_tjmax less verbose: don't warn about MSR read failure
when failure was expected, and don't report TjMax in the logs unless
debugging is enabled.