Vulkan reference count fixes in some failure cases

commit 869c6f13

vulkan: NULL check destruction of vulkan resources

If the element fails to start up, any number of vulkan resources could
have not been created.

commit 33cd016a

vulkan: make new trash objects ref the fence

Avoids gst_vulkan_fence_ref at each call site of the trash object
creation

commit 31e6dc19

vulkan/wayland: advertise the current surface size

Avoids vkswapper from creating a 0x0 output VkSurface and failing