platform/x86: intel_scu_ipc: Drop intel_scu_ipc_raw_command()

There is no user for this function so we can drop it from the driver.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>