[media] s5p-fimc: Prevent lock up caused by incomplete H/W initialization

The following ioctl sequence causes fimc_dma_run() to start processing without
complete scaler and DMA initialization which causes missing interrupt and
blocking on DQBUF:
S_FMT, STREAMON, QBUF, DQBUF, STREAMOFF, STREAMON, QBUF, DQBUF.

Fix this regression caused by moving pm_runtime* calls to start/stop_streaming
callback by making sure the fimc_m2m_resume() is always invoked when expected.

Reported-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
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>