drm/msm: update adreno firmware path in MODULE_FIRMWARE

The preferred location for Adreno firmware files is now in qcom/ subfolder,
especially now that we are adding some of them in linux-firmware.

Reported-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>
Reviewed-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>