Camera: Redirect dump to "/dev/null" instead of stdout

This SELinux context doesn't have permission to access stdout
in read/write mode. Doing so will result in violation and
subsequent failure when running in binderized mode. Switch to
 '/dev/null' which still can be used with SELinux enabled.

BUG: 35701060
Test: adb shell
/data/nativetest/VtsHalCameraProviderV2_4TargetTest/VtsHalCameraProviderV2_4TargetTest

Change-Id: Ib1cf2766ca41cfe3600ad8a4442a334dfab0e2c1