LU-10026 csdc: DoM pattern could be a combined value

LU-10026 csdc: DoM pattern could be a combined value

DoM pattern is LOV_PATTERN_MDT for now, and in the future it could
be combined with LOV_PATTERN_COMPRESS to represent a compressed
DoM component.

Fix a minor glitch for lov_getstripe_old code path (in
ll_lov_getstripe_ea_info), which intends to return the last component
stripe info but the commit abf04e7ea3 omits to correctly set the
last component stripe info before using it.

Fixes: abf04e7ea3 ("LU-14337 lov: return valid stripe_count/size for PFL files")
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Change-Id: Id0779c30c004b6979f88bf96b7b7b74a8b8c26e4