Fix for rasterpos test
This fix removes usage of dummy_input as it appears to create segmentation faults, tests skips and fails. It happens because of trying to reach part of memory which is already blocked or does not exist. Such method of working with dummy_input does not appear in any other tests with shaders and it is needless.
Signed-off-by: Viktoriia Palianytsia v.palianytsia@globallogic.com