staging: lustre: hsm: rename hai_zero() HSM function

staging: lustre: hsm: rename hai_zero() HSM function

rename hai_zero() to hai_first(). Use a better name for hai helper

Signed-off-by: JC Lafoucriere <jacques-charles.lafoucriere@cea.fr>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-3709
Reviewed-on: http://review.whamcloud.com/7254
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>