glsl: fix regression when building interface field name for SSBOs

Fixes regression cased by bb5aeb8549

We don't care about the swizzle when building the name so just skip over it.

Tested-by: Markus Wick <markus@selfnet.de>
Reviewed-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>

src/glsl/lower_ubo_reference.cpp

@@ -238,6 +238,8 @@ interface_field_name(void *mem_ctx, char *base_name, ir_rvalue *d,
       case ir_type_swizzle: {
          ir_swizzle *s = (ir_swizzle *) ir;
          ir = s->val->as_dereference();
+         /* Skip swizzle in the next pass */
+         d = ir;
          break;
       }