dxgi/tests: Some spelling fixes in ok() messages.

[Marvin]

Hi,

While running your changed tests on Windows, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?
Full results can be found at
https://testbot.winehq.org/JobDetails.pl?Key=27612

Your paranoid android.


=== w7pro64 (32 bit device) ===
device.c:1445: Test failed: SetFullscreenState failed, hr 0x887a0004.