Building without CONFIG_PM results in a harmless warning from
slightly incorrect #ifdef guards:
drivers/media/platform/vsp1/vsp1_drv.c:525:12: error: 'vsp1_pm_runtime_resume' defined but not used [-Werror=unused-function]
drivers/media/platform/vsp1/vsp1_drv.c:516:12: error: 'vsp1_pm_runtime_suspend' defined but not used [-Werror=unused-function]
This removes the existing #ifdef and instead marks all four
PM functions as __maybe_unused.