media: venus: venc: Use pmruntime autosuspend

Migrate encoder to pm-runtime autosuspend.

Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Tested-by: Vikash Garodia <vgarodia@codeaurora.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>