vrend: Fixes non-reachable default case.

This is a reupload of !474 (closed)

This fixes a regression introduced by !462 (merged) which breaks some GLES3 and GLES31 dEQP tests.

Fixes: 1b51495b ("vrend: replace if-chain by using switch/case")

Signed-off-by: Lepton Wu lepton@chromium.org Reviewed-by: Gert Wollny gert.wollny@collabora.com