[PATCH] i386: little pgtable.h consolidation vs 2/3level

Join together some common functions (pmd_page{,_kernel}) over 2level and
3level pages.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>