lpbin: Fix segfault when pipeline reused
lpbin: Fix segfault when pipeline reused

segmentation fault occured when pipeline reused at pioneer platform
the root problem is imcompleteness of pipeline unreference code at lpsink
this patch is avoid segfault and it will be solved after lpsink's unreference
code complete

:issuse addressed:
[GF-53486] segmentation fault when pipeline reused at Pioneer platform

Change-Id: I1c682936449399d9dee388f237e37e58e6eea14c
Reviewed-on: https://gpro.palm.com/21004
Tested-by: Wonchul Lee <9841bdbec9dbb2acc2dcaaa1dab0491399f0e464@lge.com>
Reviewed-by: HoonHee Lee <41497318ef67053f37c2ac0e974a3369f66d66ec@lge.com>
Reviewed-by: Jeongseok Kim <0c03ab7a1b32f29697716389c3f9549845834271@lge.com>
Tested-by: Jeongseok Kim <0c03ab7a1b32f29697716389c3f9549845834271@lge.com>

justinjoy/gst-plugins-lp,justinjoy/gst-plugins-lp