modesetting: Remove some dead code

The "if (pixmap) ..." block this commit removes is inside an
"if (pixmap == NULL) ..." block, so it will never execute.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Aaron Plattner <aplattner@nvidia.com>

hw/xfree86/drivers/modesetting/dri2.c

@@ -193,8 +193,6 @@ ms_dri2_create_buffer(DrawablePtr drawable, unsigned int attachment,
                                       pixmap_cpp,
                                       0);
         if (pixmap == NULL) {
-            if (pixmap)
-                screen->DestroyPixmap(pixmap);
             free(private);
             free(buffer);
             return NULL;