[RFC] tests in test/dm/video.c are not independent

[Heinrich Schuchardt]

Hello Simon,

looking at the tests in test/dm/video.c it seems that none of them
clears the screen before adding text and testing the hash of the frame
buffer. So it is hard to tell which output led to changes in subsequent
tests.

I think the tests should first clear the screen to start from a defined
state. This will make the tests independent of each other.

What is your view?

Best regards

Heinrich