staging: lustre: ptlrpc: gss: delete unused code

The gss code has never been built, there is no Kconfig option for it, so
delete it as code that can not build goes bad really fast.

If someone wants it back, they can revert this and fix any build errors
that might be in it.

Cc: Andreas Dilger <andreas.dilger@intel.com>
Cc: Oleg Drokin <oleg.drokin@intel.com>
Cc: hpdd-discuss <hpdd-discuss@lists.01.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>