owners.yaml: add new drivers/net/thunderbolt/ folder to webhooks
A new drivers/net/thunderbolt/ folder was created upstream with the inclusion of commit <0d0950a968009fd> "net: thunderbolt: Move into own directory"
Remove drivers/net/thunderbolt.c from webhooks when this patch is merged.
Signed-off-by: Desnes Nunes desnesn@redhat.com