Add Error parameter to load_state

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
Add errors to ram_load

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
Print load_state error

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
Add device idstr to error message for QEMU_VM_SECTION_PART and QEMU_VM_SECTION_END sections

Signed-off-by: Orit Wasserman <owasserm@redhat.com>
Add migration error description

Signed-off-by: Orit Wasserman <owasserm@redhat.com>