SST-TF high priority core count and ratios and low priority core ratios
are also per TRL level.
Cleanup the code to follow the same nameing convention as TRL.

This removes hardcoded TRL level names and variables.

No functional changes are expected.
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>