mesa: remove null check before free

Reviewed-by: Eduardo Lima Mitev <elima@igalia.com>

src/mesa/main/readpix.c

@@ -608,8 +608,7 @@ read_rgba_pixels( struct gl_context *ctx,
                                              dst, format, type);
    }
 
-   if (rgba)
-      free(rgba);
+   free(rgba);
 
 done_swap:
    /* Handle byte swapping if required */

src/mesa/main/texgetimage.c

@@ -557,8 +557,7 @@ get_tex_rgba_uncompressed(struct gl_context *ctx, GLuint dimensions,
    }
 
 done:
-   if (rgba)
-      free(rgba);
+   free(rgba);
 }