[RenderEngine] Remove unncessary const from shader.

                                float y2 = y1 + (maxOutLumi - y1) * 0.75;

                                // horizontal distances between the last three control points

                                const float h12 = x2 - x1;

                                const float h23 = maxInLumi - x2;

                                float h12 = x2 - x1;

                                float h23 = maxInLumi - x2;

                                // tangents at the last three control points

                                const float m1 = (y2 - y1) / h12;

                                const float m3 = (maxOutLumi - y2) / h23;

                                const float m2 = (m1 + m3) / 2.0;

                                float m1 = (y2 - y1) / h12;

                                float m3 = (maxOutLumi - y2) / h23;

                                float m2 = (m1 + m3) / 2.0;

                                if (nits < x0) {

                                    // scale [0.0, x0] to [0.0, y0] linearly

                                    const float slope = y0 / x0;

                                    float slope = y0 / x0;

                                    nits *= slope;

                                } else if (nits < x1) {

                                    // scale [x0, x1] to [y0, y1] linearly

                                    const float slope = (y1 - y0) / (x1 - x0);

                                    float slope = (y1 - y0) / (x1 - x0);

                                    nits = y0 + (nits - x0) * slope;

                                } else if (nits < x2) {

                                    // scale [x1, x2] to [y1, y2] using Hermite interp