arm64: dts: qcom: apq8096-db820c: Specify zap shader location

arm64: dts: qcom: apq8096-db820c: Specify zap shader location

The zap shader was previously loaded from "qcom/a530_zap.mdt", which is a
symlink to "qcom/apq8096/a530_zap.mbn". Update the DTS to reference the
actual firmware file in linux-firmware directly.

This avoids relying on the symlink and ensures a more robust firmware load
path.

Signed-off-by: Valentine Burley <valentine.burley@collabora.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20251014084808.112097-1-valentine.burley@collabora.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>