package/webkitgtk: remove upstreamed patch

The bump of webkitgtk to 2.24.3 in commit
3ff05d90 forgot to drop a patch that
was upstreamed, and is now part of 2.24.3, causing a build failure, so
let's drop this patch.

Fixes:

  http://autobuild.buildroot.net/results/4d7bffd20344f06ca719b7c8083b81053b255aa5/



Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>