media: mtk-vcodec: fix PM runtime get logic

Currently, the driver just assumes that PM runtime logic
succeded resuming the device.

That may not be the case, as pm_runtime_get_sync()
can fail (but keeping the usage count incremented).

Replace the code to use pm_runtime_resume_and_get(),
and letting it return the error code.

This way, if mtk_vcodec_dec_pw_on() fails, the logic
under fops_vcodec_open() will do the right thing and
return an error, instead of just assuming that the
device is ready to be used.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>