Current scheme of when to write and verify cpuinfo
images is unclear: we define default mode to 'fpu'
and this implies that no cpuinfo image get written
on dump and read on restore. In turn if 'cpu' or
'ins' mode specified in command line we write and
verify this image.

This is all wrong -- we need to produce image if
any mode ecxept 'none' is specified. The 'none'
mode is designed exactly for skipping cpuinfo
image production or verification.

Because any non-default mode requires explicit
--cpu-cap option to be passed we can use this
and setup new CPU_CAP_IMAGE telling criu to
write or read this image.

Note the default mode doesn't break backward
compatibility because by default we don't
write or read the image at all.
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmaill.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>