fixed typo

ScriptableRenderPipeline/LightweightPipeline/LWRP/Shaders/LightweightStandardSimpleLighting.shader

             // Unity defined keywords
             #pragma multi_compile _ DIRLIGHTMAP_COMBINED
             #pragma multi_compile _ LIGHTMAP_ON
-            #pragma multi_compile _ _SHADOW_ENABLED
+            #pragma multi_compile _ _SHADOWS_ENABLED
 
             //--------------------------------------
             // GPU Instancing