ASoC: msm: qdsp6v2: avoid returning 0-size cal block

When looking for calibration data blocks, check for size being
non-zero before returning to the caller.

Change-Id: I8f94d17455000c0f15e53bf7685b21a7b1c1955e
Signed-off-by: Banajit Goswami <bgoswami@codeaurora.org>