[media] s5p-mfc: check mfc bus ctrl before reset

during reset sequence, it is advisable to follow the below
sequence, in order to avoid unexpected behavior from MFC
. set SFR 0x7110 MFC_BUS_RESET_CTRL 0x1
  // wait for REQ_STATUS to be 1
. get SFR 0x7110 MFC_BUS_RESET_CTRL 0x3
  // reset now

Signed-off-by: Kiran AVND <avnd.kiran@samsung.com>
Signed-off-by: Arun Kumar K <arun.kk@samsung.com>
Signed-off-by: Kamil Debski <k.debski@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>