[kwinglutils] Drop eglResolveFunctions

Summary:
Method doesn't do anything. If at some point we want to resolve egl
functions again, it should be done in the Platform, just like
glxResolveFunctions is nowadays done in the platform.

Reviewers: #kwin, #plasma

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D3391