nfs41: reset the session slot table

Separated from nfs41: schedule async session reset

Do not kfree the session slot table upon session reset, just re-initialize it.
Add a boolean to nfs4_proc_create_session to inidicate if this is a
session reset or a session initialization.

Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>