Implement a POWER7 optimised copy_page using VMX. We copy a cacheline
at a time using VMX loads and stores.

Signed-off-by: Anton Blanchard <redacted>
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How do we want to handle per machine optimised functions? I create
yet another feature bit, but feature bits might get out of control
at some point.

Yeah, I'm pretty against CPU_FTR_POWER7.  Every loon is going to attach
anything POWER7 to it.  

I'm keen to see it setup in  __setup_cpu_power7.  Either a function
pointer or use the patch_instruction infrastructure to avoid indirect
function calls on small copies.  

Mikey