media: v4l2-dev.h: fix symbol collision in media_entity_to_video_device()
A recent change to the media_entity_to_video_device() macro breaks some
use-cases for the macro due to a symbol collision. Before the change
this worked:
While after the change it results in a compiler error "error: 'struct
video_device' has no member named 'link'; did you mean 'lock'?". While
the following still works after the change.