media: amphion: Remove dummy PM handling

media: amphion: Remove dummy PM handling

Since commit 63d00be69348fda4 ("PM: runtime: Allow unassigned
->runtime_suspend|resume callbacks"), unassigned
.runtime_{suspend,resume}() callbacks are treated the same as dummy
callbacks that just return zero.
Unassigned system sleep callbacks were always treated the same as dummy
callbacks that just return zero.

As the driver has no other PM callbacks than dummy callbacks, all PM
handling can be removed.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Ming Qian <ming.qian@oss.nxp.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>