radv: fix accessing NULL pointers when destroy the VRS image

radv: fix accessing NULL pointers when destroy the VRS image

Detected by UBSAN.

../src/amd/vulkan/radv_private.h:2939:1: runtime error: member access
within null pointer of type 'struct radv_device_memory'

../src/amd/vulkan/radv_private.h:2926:1: runtime error: member access
within null pointer of type 'struct radv_buffer'

../src/amd/vulkan/radv_private.h:2945:1: runtime error: member access
within null pointer of type 'struct radv_image'

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13965>