platform/x86: intel_pmc_core: Add slp_s0_offset attribute back to tgl_reg_map

If platforms such as Tiger Lake has sub-states of S0ix, then attributes
such as slps0_dbg_offset become invalid. But slp_s0_offset is still
valid as it is used to get the pmcdev_base_addr.

Hence, add back slp_s0_offset and remove slps0_dbg_offset attributes.

Cc: Chen Zhou <chenzhou10@huawei.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: David E. Box <david.e.box@intel.com>
Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>