kmssink: Add Amlogic upstreamer DRM driver support

Amlogic Upstream driver is named meson, not to be confuse with the build
system.
diff --git a/sys/kms/gstkmssink.c b/sys/kms/gstkmssink.c
index a4129c7..1b5f18d 100644
--- a/sys/kms/gstkmssink.c
+++ b/sys/kms/gstkmssink.c
@@ -168,7 +168,7 @@
 {
   static const char *drivers[] = { "i915", "radeon", "nouveau", "vmwgfx",
     "exynos", "amdgpu", "imx-drm", "rockchip", "atmel-hlcdc", "msm",
-    "xilinx_drm", "vc4",
+    "xilinx_drm", "vc4", "meson",
   };
   int i, fd = -1;