QEMUFileRDMA also has read and write modes. This function is now
shared to reduce code duplication.
Reviewed-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Chegu Vinod <chegu_vinod@hp.com> Tested-by: Chegu Vinod <chegu_vinod@hp.com> Tested-by: Michael R. Hines <mrhines@us.ibm.com> Signed-off-by: Michael R. Hines <mrhines@us.ibm.com> Signed-off-by: Juan Quintela <quintela@redhat.com>