platform/x86: intel_pmc_core: Remove duplicate 'if' to create debugfs entry

A debugfs entry for substate_live_status_registers is created only if
the platform has sub-states, which requires the same condition to create
substate_status_registers debugfs entry. Hence remove the redundant
condition and re-use the existing one.

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>