mm/vmalloc: explicitly identify vm_map_ram area when shown in /proc/vmcoreinfo

mm/vmalloc: explicitly identify vm_map_ram area when shown in /proc/vmcoreinfo

Now, by marking VMAP_RAM in vmap_area->flags for vm_map_ram area, we can
clearly differentiate it with other vmalloc areas.  So identify
vm_map_area area by checking VMAP_RAM of vmap_area->flags when shown in
/proc/vmcoreinfo.

Meanwhile, the code comment above vm_map_ram area checking in s_show() is
not needed any more, remove it here.

Link: https://lkml.kernel.org/r/20230206084020.174506-5-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Dan Carpenter <error27@gmail.com>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>