platform/x86: intel_pmc_ipc: Use BIT() macro

Use BIT() and BIT_MASK() macros for definitions.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>