ExternalCameraDevice: increase max bytes per pixel

This fixes some USB external camera which fails to initialize with:

  I ExtCamDevSsn@3.4: configureV4l2StreamLocked: V4L2 buffer size is 614989
  E ExtCamDevSsn@3.4: configureV4l2StreamLocked: V4L2 buffer size: 614989 looks invalid. Expected maximum size: 614400
  E ExtCamDevSsn@3.4: V4L configuration failed!, format:MJPG, w 640, h 480

BUG=b:326773369, b:309244873
Test: Manual camera operation verification

Change-Id: I532bef429792f5a841034a4f3d4eadfa6ed78b2a
Reviewed-by: Tomasz Nowicki <tnowicki@google.com>
Tested-by: Tomasz Nowicki <tnowicki@google.com>
Reviewed-by: Konrad Adamczyk <konrada@google.com>
diff --git a/camera/device/default/ExternalCameraDeviceSession.h b/camera/device/default/ExternalCameraDeviceSession.h
index 1c6ed06..ed84931 100644
--- a/camera/device/default/ExternalCameraDeviceSession.h
+++ b/camera/device/default/ExternalCameraDeviceSession.h
@@ -122,7 +122,7 @@
 
     static const int kMaxProcessedStream = 2;
     static const int kMaxStallStream = 1;
-    static const uint32_t kMaxBytesPerPixel = 2;
+    static const uint32_t kMaxBytesPerPixel = 3;
 
     class BufferRequestThread : public SimpleThread {
       public: