Thermal: x86_pkg_temp: Limit number of pkg temp zones

Although it is unlikley that physical package id is set to some
arbitary number, it is better to prevent in anycase. Since package
temp zones use this in thermal zone type and for allocation, added
a limit.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>