drm/panfrost: Use delayed timer as default in devfreq profile

Devfreq framework supports 2 modes for monitoring devices.
Use delayed timer as default instead of deferrable timer
in order to monitor the GPU status regardless of CPU idle.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210105164111.30122-1-lukasz.luba@arm.com