Revert duplicate "mm/hugetlb.c must #include <asm/io.h>"

This reverts commit 7cb93181, since we
did that patch twice, and the problem was already fixed earlier by
78a34ae2.

Reported-by: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>