[PATCH] gcc4 compile fix for recent ia64 xpc changes

Gcc4 doesn't like volatile casts as lvalues.  Make the structure members
volatile instead.

Signed-off-by: Dave Jones <davej@redhat.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>