[media] media: ti-vpe: vpdma: Fix race condition for firmware loading

vpdma_create API is supposed to allocated the struct vpdma_data and
return it to the driver. Also, it would call the callback function
when the VPDMA firmware is loaded.

Typically, VPE driver have following function call:
    dev->vpdma = vpdma_create(pdev, firmware_load_callback);
And the callback implementation would continue the probe further.
Also, the dev->vpdma is accessed from the callback implementation.

This may lead to race condition between assignment of dev->vpdma
and the callback function being triggered.
This would lead to kernel crash because of NULL pointer access.

Fix this by passing a driver wrapped &vpdma_data instead of allocating
inside vpdma_create.
Change the vpdma_create prototype accordingly and fix return paths.

Also, update the VPE driver to use the updated API and
initialize the dev->vpdma before hand so that the race condition
is avoided.

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>