Re-allow INVALID modifier in import path.  The legacy import path
(createImageFromFds()), which is used by android, uses the INVALID
modifier.  Previously we would ignore this and just setup the imported
buffer as linear.  Restore this behavior to unbreak the legacy import
path.

Fixes: 98910626

 freedreno/a6xx: Implement layout for DRM_FORMAT_MOD_QCOM_COMPRESSED
Signed-off-by: Rob Clark <robdclark@chromium.org>
Tested-by: Marge Bot <mesa/mesa!3817>
Part-of: <mesa/mesa!3817>