EEVEE: Fix wrong sss component being affected by alpha

This fixes NaNs / blown up values when using alpha-hashed transparency
or alpha clip with SSS.

source/blender/draw/engines/eevee/shaders/surface_frag.glsl

@@ -79,7 +79,7 @@ void main()
 #endif
 
 #ifndef USE_ALPHA_BLEND
-  float alpha_div = 1.0 / max(1e-8, alpha);
+  float alpha_div = safe_rcp(alpha);
   outRadiance.rgb *= alpha_div;
   ssrData.rgb *= alpha_div;
 #  ifdef USE_SSS

source/blender/gpu/shaders/material/gpu_shader_material_principled.glsl

@@ -193,7 +193,7 @@ void node_bsdf_principled(vec4 base_color,
   result.radiance *= alpha;
   result.ssr_data.rgb *= alpha;
 #  ifdef USE_SSS
-  result.sss_irradiance *= alpha;
+  result.sss_albedo *= alpha;
 #  endif
 }