tools/power/x86/intel-speed-select: Use mailbox for CLOS_PM_QOS_CONFIG

Use mailbox to read/write CLOS_PM_QOS_CONFIG instead of read/write to
MMIO offset.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>