staging: lustre: refactor libcfs initialization.

Many lustre modules depend on libcfs having initialized
properly, but do not explicit check that it did.
When lustre is built as discrete modules, this does not
cause a problem because if the libcfs module fails
initialization, the other modules don't even get loaded.

When lustre is compiled into the kernel, all module_init()
routines get run, so they need to check the required initialization
succeeded.

This patch splits out the initialization of libcfs into a new
libcfs_setup(), and has all modules call that.

The misc_register() call is kept separate as it does not allocate any
resources and if it fails, it fails hard - no point in retrying.
Other set-up allocates resources and so is best delayed until they
are needed, and can be worth retrying.

Ideally, the initialization would happen at mount time (or similar)
rather than at load time.  Doing this requires each module to
check dependencies when they are activated rather than when
they are loaded.  Achieving that is a much larger job that would
have to progress in stages.

For now, this change ensures that if some initialization in libcfs
fails, other modules will fail-safe.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>