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

This reverts commit 7cb93181629c613ee2b8f4ffe3446f8003074842, since we
did that patch twice, and the problem was already fixed earlier by
78a34ae29bf1c9df62a5bd0f0798b6c62a54d520.

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