staging: lustre: change some LIBCFS_ALLOC calls to k?alloc(GFP_KERNEL)

When an allocation happens from process context rather than
filesystem context, it is best to use GFP_KERNEL rather than
LIBCFS_ALLOC() which always uses GFP_NOFS.
This include initialization during, or prior to, mount,
and code run from separate worker threads.

So for some of these cases, switch to kmalloc, kvmalloc, or
kvmalloc_array() as appropriate.
In some cases we preserve __GFP_ZERO (via kzalloc/kvzalloc), but in
others it is clear that allocated memory is immediately initialized.

In each case, the matching LIBCFS_FREE() is converted to
kfree() or kvfree()

This is just a subset of locations that need changing.
As there are quite a lot, I've broken them up into several
ad-hoc sets to avoid review-fatigue.

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