platform/x86: intel_scu_ipc: Fix interrupt support

platform/x86: intel_scu_ipc: Fix interrupt support

commit e48b72a568bbd641c91dad354138d3c17d03ee6f upstream.

Currently the driver has disabled interrupt support for Tangier but
actually interrupt works just fine if the command is not written twice
in a row. Also we need to ack the interrupt in the handler.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>