thermal/x86_pkg_temp: Cleanup thermal interrupt handling

Wenn a package is removed nothing restores the thermal interrupt MSR so
the content will be stale when a CPU of that package becomes online again.

Aside of that the work function reenables interrupts before acknowledging
the current one, which is the wrong order to begin with.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>