drm/amdkfd: Fix pasid value leak

Curret kfd does not allocate pasid values, instead uses pasid value for each
vm from graphic driver. So should not prevent graphic driver from releasing
pasid values since the values are allocated by graphic driver, not kfd driver
anymore. This patch does not stop graphic driver release pasid values.

Fixes: 77b5e447(drm/amdkfd: Have kfd driver use same PASID values from
graphic driver)

Signed-off-by: Xiaogang Chen <xiaogang.chen@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>