Add threading to camera.

Camera now has special synchronized threads to enqueue
buffers and dequeue buffers.

BUG: 29334616
TEST: manually tested with test app

Change-Id: Ibce14cd6b269c4d26403534b3f7985914263bf2b
diff --git a/modules/camera/3_4/v4l2_wrapper.cpp b/modules/camera/3_4/v4l2_wrapper.cpp
index 3d7ba85..40db4f6 100644
--- a/modules/camera/3_4/v4l2_wrapper.cpp
+++ b/modules/camera/3_4/v4l2_wrapper.cpp
@@ -156,8 +156,9 @@
   HAL_LOG_ENTER();
 
   if (!format_) {
-    HAL_LOGE("Stream format must be set to turn off stream.");
-    return -ENODEV;
+    // Can't have turned on the stream wihtout format being set,
+    // so nothing to turn off here.
+    return 0;
   }
 
   int32_t type = format_->type();