drm/amdkfd: Change pasid's type to unsigned int

[Fenghua Yu]

Hi, Felix,

On Fri, May 22, 2020 at 03:40:06PM -0400, Felix Kuehling wrote:
> Hi Fenghua,
> 
> The PASID width in KFD is currently limited to 16 bits. I believe this
> reflects what our hardware can handle. KFD will never allocate a PASID
> bigger than 16 bits. That said, I'm OK with changing this field in the
> kfd_process structure to unsigned int. Generally, I find uint16_t in
> structures not very useful except in tightly packed structures such as
> packet formats or ioctl arguments.

Thank you very much for your insight!

I'm writing the patch set to define pasid as "unsigned int" consistently
in iommu. I'll put the amdkfd changes (only a few changes including this
pasid change in struct kfd_processin) one patch and send it to you for
review.

-Fenghua