x86: msr-index.h: Define MSR_PKG_CST_CONFIG_CONTROL

define MSR_PKG_CST_CONFIG_CONTROL (0xE2),
which is the string used by Intel Documentation.

We use this MSR in intel_idle and turbostat by a previous name,
to be updated in the next patch.

Cc: x86@kernel.org
Signed-off-by: Len Brown <len.brown@intel.com>