Set cameraserver optional. am: 5d96a546c0 am: b515351410 am: d82bd5d459 am: 4ebbf4fda5

Original change: https://android-review.googlesource.com/c/platform/system/libhidl/+/1465848

Change-Id: I41846f57a1b5fde084f76782553b3547622dc1f8