gpu: Rename the last bits from gpu to nvidia-gpu

Let's specifically name the `gpu` runtime class as `nvidia-gpu`.  By
doing this we keep the door open and ease the life of the next vendor
adding GPU support for Kata Containers.

Fixes: #6553

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

tools/packaging/kata-deploy/runtimeclasses/kata-runtimeClasses.yaml

@@ -93,8 +93,8 @@ scheduling:
 kind: RuntimeClass
 apiVersion: node.k8s.io/v1
 metadata:
-    name: kata-qemu-gpu
-handler: kata-qemu-gpu
+    name: kata-qemu-nvidia-gpu
+handler: kata-qemu-nvidia-gpu
 overhead:
     podFixed:
         memory: "160Mi"