drm/amdkfd: always include uapi header in priv.h

The header usr/linux/kfd_ioctl.h is a duplicate of uapi/linux/kfd_ioctl.h.
And it is actually not a file in the source code tree.
Ideally, the usr version should be updated whenever the source code is recompiled.

However, I have noticed a discrepancy between the two headers
even after rebuilding the kernel.

This commit modifies kfd_priv.h to always include the header from uapi to ensure
the latest changes are reflected. We should always include the source
code header other than the duplication.

Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>