drivers: video: allow to specify individual ep with ID >= 0

This define the enum values so that they never clash with custom
endpoint IDs passed numerically, for devices that supports more
than one IN or OUT enpoint.

This also documents semantics for VIDEO_EP_IN/OUT/ALL/NONE,
while renaming VIDEO_EP_ANY to VIDEO_EP_ALL to remove the
ambiguity when there are several IN and/or OUT endpoints.

Signed-off-by: Josuah Demangeon <me@josuah.net>