staging: lustre: Replace aligned packed with packed

Replace __aligned__((packed)) with __packed in order to follow
the best practices and to fix checkpatch.pl warning:
'WARNING: __packed is preferred over __attribute__((packed))'

Signed-off-by: Cristina Moraru <cristina.moraru09@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>