There was a problem with diag modules, that were auto-loaded on dump and
put some data into uevent sockets thus causing the dump to fail on that
socket. The solution that time was to call modprobe in advance to make
sure the diag modules are there.

This turned out to be not nice solution as modprobe may fail if the module
is missing and the requred functionality is built-in.

To handle this for diag stuff it is mush faster and more reliable to ping
the kernel with simple diag request and check that it reqched the required
module.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>