tools/power turbostat: fix SPR PC6 limits

Sapphire Rapids Xeon (SPR) supports 2 flavors of PC6 - PC6N (non-retention) and
PC6R (retention). Before this patch we used ICX package C-state limits, which
was wrong, because ICX has only one PC6 flavor. With this patch, we use SKX PC6
limits for SPR, because they are the same.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>