mm_init.c: avoid ifdef-inside-macro-expansion

gcc-3.2:

  mm/mm_init.c:77:1: directives may not be used inside a macro argument
  mm/mm_init.c:76:47: unterminated argument list invoking macro "mminit_dprintk"
  mm/mm_init.c: In function `mminit_verify_pageflags_layout':
  mm/mm_init.c:80: `mminit_dprintk' undeclared (first use in this function)
  mm/mm_init.c:80: (Each undeclared identifier is reported only once
  mm/mm_init.c:80: for each function it appears in.)
  mm/mm_init.c:80: syntax error before numeric constant

Also fix a typo in a comment.

Reported-by: Adrian Bunk <bunk@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>