package/opencv3: bump to version 3.4.6

- Remove patch (already in version)
- Update hash of license file (update in year:
  https://github.com/opencv/opencv/commit/14d943f588474cee3cdb8f91e8f7fb7e8af7ad8b

)

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>