Documentation: remove SH-5 index entries

Documentation: remove SH-5 index entries

Remove SH-5 documentation index entries following the removal
of SH-5 source code.

Error: Cannot open file ../arch/sh/mm/tlb-sh5.c
Error: Cannot open file ../arch/sh/mm/tlb-sh5.c
Error: Cannot open file ../arch/sh/include/asm/tlb_64.h
Error: Cannot open file ../arch/sh/include/asm/tlb_64.h

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/71e1f336-ef5c-f5e9-25cf-16bd4439b9f9@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>