verbose argument to sd_synchronize_cache

sd_synchronize_cache() is always called with verbose=1, so this argument should go away. But do we really want to be that verbose here? IMHO we should remove the argumet and the printks..

It can take a while to synchronise the cache on monster arrays, so printing something while we do it on shutdown is a good idea (unless you want the "my machine takes ages to shut down" type of bug reports).

The non-verbose part was for exposing the synchronise via an ioctl (which I haven't got around to writing yet) on the grounds that anyone doing the ioctl knows what's going on and doesn't need a kernel message telling them.

James