m68knommu: add pgtable_t

  CC      init/main.o
In file included from include2/asm/uaccess.h:8,
                 from include/linux/poll.h:13,
                 from include/linux/rtc.h:113,
                 from include/linux/efi.h:19,
                 from linux-2.6/init/main.c:43:
include/linux/mm.h:1151:
error: expected declaration specifiers or '...' before 'pgtable_t'

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reported-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>