anv: remove dummy VK_DEBUG_MARKER_EXT entry points

The vkCmdDbgMarker{Begin,End} symbols are exported, yet the json does no
advertise that the driver supports the extension. Furthermore the
functions are empty stubs.

Remove those until we get a proper implementation and json notation.

Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Emil Velikov <emil.velikov@collabora.com>

src/intel/vulkan/anv_device.c

@@ -1798,23 +1798,3 @@ void anv_DestroyFramebuffer(
 
    anv_free2(&device->alloc, pAllocator, fb);
 }
-
-void vkCmdDbgMarkerBegin(
-    VkCommandBuffer                              commandBuffer,
-    const char*                                 pMarker)
-   __attribute__ ((visibility ("default")));
-
-void vkCmdDbgMarkerEnd(
-   VkCommandBuffer                              commandBuffer)
-   __attribute__ ((visibility ("default")));
-
-void vkCmdDbgMarkerBegin(
-    VkCommandBuffer                              commandBuffer,
-    const char*                                 pMarker)
-{
-}
-
-void vkCmdDbgMarkerEnd(
-    VkCommandBuffer                              commandBuffer)
-{
-}