ASoC: soc-pcm: Add NULL check in BE reparenting

stable inclusion
from stable-v5.10.159
commit f6f45e538328df9ce66aa61bafee1a5717c4b700
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7NTXH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f6f45e538328df9ce66aa61bafee1a5717c4b700



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[ Upstream commit db8f91d4 ]

Add NULL check in dpcm_be_reparent API, to handle
kernel NULL pointer dereference error.
The issue occurred in fuzzing test.

Signed-off-by: Srinivasa Rao Mandadapu <quic_srivasam@quicinc.com>
Link: https://lore.kernel.org/r/1669098673-29703-1-git-send-email-quic_srivasam@quicinc.com


Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>