drm/msm/adreno: Fix error return if missing firmware-name

-ENODEV is used to signify that there is no zap shader for the platform,
and the CPU can directly take the GPU out of secure mode.  We want to
use this return code when there is no zap-shader node.  But not when
there is, but without a firmware-name property.  This case we want to
treat as-if the needed fw is not found.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/604564/