[media] s5p-fimc: Fix fimc-lite system wide suspend procedure

Only suspend the video pipeline devices if they were active before
the pm.suspend() helper is called. This patch prevents following error:

/# echo mem > /sys/power/state
[   34.965000] PM: Syncing filesystems ... done.
[   35.035000] Freezing user space processes ... (elapsed 0.01 seconds) done.
...
[   35.105000] dpm_run_callback(): platform_pm_suspend+0x0/0x5c returns -22
[   35.105000] PM: Device exynos-fimc-lite.1 failed to suspend: error -22
[   35.105000] PM: Some devices failed to suspend

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>