video: vt8500: fix error handling in probe()

We shouldn't kfree(fbi) because that was allocated with devm_kzalloc().
There were several error paths which returned directly instead of
releasing resources.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>