linux-next: 1ea0704e (ptep_modify_prot transaction abstraction) breaks no-mmu

["Mike Frysinger" <vapier.adi@gmail.com>]

the functions added to asm-generic/pgtable.h are only used by
mm/mprotect.c (a MMU-only file), but they were not added inside of the
CONFIG_MMU ifdef block.  since the functions rely on things inside of
CONFIG_MMU (the lines just above in pgtable.h), we get build failure
on all no-mmu setups:
  CC      init/main.o
In file included from include/asm/pgtable.h:94,
                 from include/linux/mm.h:39,
                 from include/asm/dma.h:39,
                 from include/linux/bootmem.h:8,
                 from init/main.c:27:
include/asm-generic/pgtable.h: In function '__ptep_modify_prot_start':
include/asm-generic/pgtable.h:210: error: implicit declaration of
function 'ptep_get_and_clear'
include/asm-generic/pgtable.h:210: error: incompatible types in return
make[1]: *** [init/main.o] Error 1
make: *** [init/main.o] Error 2
-mike