[Backport 7.x.x] Fix issue with light layers > 7 in the deferred path (#1093)

* Mask layers to consider only the supported 8 bits

* changelog

Co-authored-by: sebastienlagarde <sebastien@unity3d.com>

Author: FrancescoC-unity

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -94,6 +94,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed an issue where manipulating the color wheels in a volume component would reset the cursor every time.
 - Fixed an issue where static sky lighting would not be updated for a new scene until it's reloaded at least once.
 - Fixed missing include guards in shadow hlsl files.
+- Fixed issue with light layers bigger than 8 (and above the supported range). 
 
 ### Changed
 - Rejecting history for ray traced reflections based on a threshold evaluated on the neighborhood of the sampled history.

com.unity.render-pipelines.high-definition/Runtime/Material/Lit/Lit.hlsl

@@ -640,7 +640,8 @@ void EncodeIntoGBuffer( SurfaceData surfaceData
     outGBuffer3 *= GetCurrentExposureMultiplier();
 
 #ifdef LIGHT_LAYERS
-    OUT_GBUFFER_LIGHT_LAYERS = float4(0.0, 0.0, 0.0, builtinData.renderingLayers / 255.0);
+    // Note: we need to mask out only 8bits of the layer mask before encoding it as otherwise any value > 255 will map to all layers active
+    OUT_GBUFFER_LIGHT_LAYERS = float4(0.0, 0.0, 0.0, (builtinData.renderingLayers & 0x000000FF) / 255.0);
 #endif
 
 #ifdef SHADOWS_SHADOWMASK