Revert "Fix assert when setting custom EGL parameters"

This reverts commit 2be29851033313fd54eccbfb5f444bc26da3cba0.

Remove unnecessray change to winsys-egl
Remove configuration options method
Reordered code in cogl-renderer to prevent requiring setting the cogl backend. Fixed some coding style issues in cogl-winsys-egl-rpi.c