ASoC: msm: qdsp6v2: Check for null pointers

Add check for null data pointer in
adm_callback() and log error message if
true.

CRs-Fixed: 575222
Change-Id: I88a4d19cc2e78610249e404bce93831557995fab
Signed-off-by: Kenneth Westfield <kwestfie@codeaurora.org>