For deinterlacing operation, each operation needs 2 fields in the
history. This is achieved by holding three buffers in
ctx->src_vbs[0,1,2] (f,f-1,f-2)

This is achieved by using the ctx->sequence which gets reset via the
s_fmt ioctl.

These buffers are dequeued in stream OFF by calling free_vbs()
But the corresponding references aren't removed anywhere.

When application tries to stream ON and OFF continuously, s_fmt ioctl
won't be called and it won't setup the srcdst parameters.

Setting source/destination parameters in stream ON ioctl would make
sure that the context is re-initialized before it is being used by
the driver.

Signed-off-by: Nikhil Devshatwar <nikhil.nd@ti.com>
Signed-off-by: Benoit Parrot <bparrot@ti.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>