Remove unused struct fields in VoxelGIData

This reduces the struct size from 112 bytes to 96 bytes.

servers/rendering/renderer_rd/shaders/gi.glsl

@@ -68,19 +68,15 @@ sdfgi;
 #define MAX_VOXEL_GI_INSTANCES 8
 
 struct VoxelGIData {
-	mat4 xform;
-	vec3 bounds;
-	float dynamic_range;
+	mat4 xform; // 64 - 64
 
-	float bias;
-	float normal_bias;
-	bool blend_ambient;
-	uint texture_slot;
+	vec3 bounds; // 12 - 76
+	float dynamic_range; // 4 - 80
 
-	uint pad0;
-	uint pad1;
-	uint pad2;
-	uint mipmaps;
+	float bias; // 4 - 84
+	float normal_bias; // 4 - 88
+	bool blend_ambient; // 4 - 92
+	uint mipmaps; // 4 - 96
 };
 
 layout(set = 0, binding = 16, std140) uniform VoxelGIs {