soundwire: intel: add link_list to handle interrupts with a single thread

In MSI mode, the use of separate handlers and threads for the Intel
IPC, stream and SoundWire shared interrupt leads to timeouts and lost
interrupts.

The solution is to merge all interrupt handling across all links with
a single thread function. The use of a linked list enables this thread
function to walk through all contexts and figure out which link needs
attention.
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191212014507.28050-9-pierre-louis.bossart@linux.intel.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

include/linux/soundwire/sdw_intel.h

@@ -70,6 +70,7 @@ struct sdw_intel_link_res;
  * @handle: ACPI parent handle
  * @links: information for each link (controller-specific and kept
  * opaque here)
+ * @link_list: list to handle interrupts across all links
  */
 struct sdw_intel_ctx {
 	int count;
@@ -77,6 +78,7 @@ struct sdw_intel_ctx {
 	u32 link_mask;
 	acpi_handle handle;
 	struct sdw_intel_link_res *links;
+	struct list_head link_list;
 };
 
 /**