powerpc: Move include/asm-ppc64/vio.h to include/asm-powerpc/vio.h

Move include/asm-ppc64/vio.h to include/asm-powerpc/vio.h, that's it.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>