Linus removed the "volatile" statement from the definition of the
__raw_* IO accessors on ppc64, which cause some real bad optisations to
happen in some fbdev's like matroxfb to happen (just imagine that
matroxfb loops reading an IO register waiting for a bit to change).

The __raw_xxxx() functions still want ordered accesses (they avoid the
byteswap, though)
Signed-off-by: Benjamin Herrenschmidt <benh@kenrel.crashing.org>