tools/power/turbostat: Abstract hardcoded TDP value

Different hardcoded TDP values are used when TDP can not be retrieved
from the hardware.

Abstract hardcoded TDP value.

Delete CPU model checks in get_tdp_intel().

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>