namei: Remove icreate tfd hack

Currently, the namei icreate routine creates a fake FdHandle_t for a
SetLinkCount call if we're creating a linktable. In the past this was
probably done because we did not want to open a "real" fdP ,since that
would mean opening another file descriptor, when we already had a file
descriptor (from the creating afs_open call).

This is a problem in the salvager, since it means that we can reach
ihandle code before the ihandle package has been initialized.
Specifically, we can reach icreate -> namei_SetLinkCount -> ih_fdsync.
If we reach ih_fdsync without the ihandle package being initialized,
we assert and dump core.

The ihandle package assumes that we've already initialized it if we
reach any ihandle code, since creating any IHandle_t causes the
package to initialize. But since namei_icreate fakes its own IHandle_t
and FdHandle_t structures, that doesn't happen.

So, to avoid this, stop faking our FdHandle_t and create a real one.
Since we have ih_attachfd, we can create a real FdHandle_t with our
existing file descriptor.

Change-Id: I7a8c1e0ed1ee8e5c8ce2e165b9493811d5d2435d
Reviewed-on: http://gerrit.openafs.org/10213
Reviewed-by: D Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>