Camera: Handle the case of calling Uid being cameraserver

With HAL1-camera2 legacy implementation, the getCameraCharacteristics
may be called without camera permission. So the cameraserver's Uid is
used in that case.

AppOpsManager returns MODE_IGNORED when the cameraserver's Uid is passed.
Do not treat this as an error case.

Bug: 153511543
Test: On Pixel 2 device, run "adb root; adb shell setprop
persist.camera.HAL3.enabled 0; adb reboot", then "atest
cts/tests/camera/CaptureRequestTest"

Change-Id: I29aaa2045b14233537c737bf0738fbc32422540e