Staging: lustre: Replace kzalloc followed by memcpy with kmemdup

Replace kzalloc followed by memcpy by kmemdup. This patch was generated
by 'make coccicheck'

Signed-off-by: Niranjan Dighe <ndighe@visteon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>