opencv: Remove hash file

Since the tarball we download is generated from GitHub, there's no
saying that the tarball won't differ in a month from now.
So the hash has no value there.

An update to the manual should be done.

Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/opencv/opencv.hash

@@ -1,3 +0,0 @@
-# From https://github.com/itseez/opencv/archive/2.4.10/
-md5	3346a59310d788d3845f4fd6043a108a	opencv-2.4.10.tar.gz
-sha1	a0c2d5944364fc4f26b6160b33c03082b1fa08c1	opencv-2.4.10.tar.gz