kmscube: bump SRCREV to get offscreen rendering to work

Newer kmscube added support for offscreen rendering, using render nodes.
Bump up SRCREV to get this feature supported in oe-core.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>