The ornamental design for LED fixture, as shown and described.
1. LED fixture
1.1 is a perspective view showing my design;
1.2 is a front elevational view thereof
1.3 is a rear elevational view thereof;
1.4 is a right side elevational view thereof;
1.5 is a left side elevational view thereof;
1.6 is a top plan view thereof;
1.7 is a bottom plan view thereof.
The dash-dot-dash broken lines shown represent the bounds of the claim and forms no part thereof and the dashed broken lines shown therein illustrate portions of the luminaire that form no part of the claimed design.