virtio: add 64-bit virtio helpers for 1.0
virtio: add 64-bit virtio helpers for 1.0

64-bit fields are to be treated as two 32-bit fields, with low 32 bit
part followed by the high 32 bit part.

Signed-off-by: Nikunj A Dadhania <e2f4a5db9b4735182a88051d1e7a3599f9eac9db@linux.vnet.ibm.com>
Reviewed-by: Thomas Huth <9e65be74847981e55b2564b6266c57d86d3bac05@redhat.com>
Signed-off-by: Alexey Kardashevskiy <ac1fc56530d7d037e1ea666f130daca22d72f964@ozlabs.ru>
Signed-off-by: Nikunj A Dadhania <e2f4a5db9b4735182a88051d1e7a3599f9eac9db@linux.vnet.ibm.com>

open-power-host-os/slof,open-power-host-os/slof,open-power-host-os/slof,open-power-host-os/slof