s5k3l6xx: use pm_runtime_force_suspend/resume for system suspend

Fix the broken system suspend implementation similar to
https://lore.kernel.org/linux-media/20211109125505.2682553-1-martin.kepplinger@puri.sm/T/#u
and
https://lore.kernel.org/linux-media/20211109131013.2684058-3-martin.kepplinger@puri.sm/T/#u
2 jobs for 20211110_pm_fixes in 116 minutes and 58 seconds (queued for 1 second)
Status Name Job ID Coverage
  Build
passed build:aarch64 #377220
librem5

00:39:48

passed build:deb #377221
librem5:arm64

01:17:10