x86: page_types.h unification of declarations

Impact: unification of declarations, cleanup

Unification of declarations:
 moved init_memory_mapping, initmem_init and free_initmem from
page_XX_types.h to page_types.h

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andrew Morton <akpm@linux-foundation.org>
LKML-Reference: <1239693869.3033.31.camel@ht.satnam>
Signed-off-by: Ingo Molnar <mingo@elte.hu>