media: intel/ipu6: Remove pin_ready function pointer

We can call ipu6_isys_queue_buf_ready() directly. The only current
usage is pin_ready pointer is to check if pin was prepared before
IPU6_FW_ISYS_RESP_TYPE_PIN_DATA_READY interrupt, we can use queue
pointer for that purpose.

Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>