drm-tests: add support for UYVY and remove MT21

Intel supports it and we can pretty easily test it.  We can't
test MT21 at this point since it's swizzled NV12, and gbm can't
allocate it.

BUG=b:37526302
TEST=./plane_test -f UYVY draws striped pattern

Change-Id: I4f2c0a1b4790e41a71a497572eb5ff10f5525790
Reviewed-on: https://chromium-review.googlesource.com/489810
Commit-Ready: Gurchetan Singh <gurchetansingh@chromium.org>
Tested-by: Gurchetan Singh <gurchetansingh@chromium.org>
Reviewed-by: Dongseong Hwang <dongseong.hwang@intel.com>
Reviewed-by: Daniele Castagna <dcastagna@chromium.org>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
2 files changed