drm/prime: Pass the right module owner through to dma_buf_export()

drm/prime: Pass the right module owner through to dma_buf_export()

dma_buf_export() adds a reference to the owning module to the dmabuf (to
prevent the driver from being unloaded whilst a third party still refers
to the dmabuf). However, drm_gem_prime_export() was passing its own
THIS_MODULE (i.e. drm.ko) rather than the driver. Extract the right
owner from the device->fops instead.

v2: Use C99 initializers to zero out unset elements of
dma_buf_export_info
v3: Extract the right module from dev->fops.

Testcase: igt/vgem_basic/unload
Reported-by: Petri Latvala <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>
Cc: Petri Latvala <[email protected]>
Cc: Christian König <[email protected]>
Cc: [email protected]
Tested-by: Petri Latvala <[email protected]>
Reviewed-by: Petri Latvala <[email protected]>
Reviewed-by: Christian König <[email protected]>
Signed-off-by: Daniel Vetter <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]