drm/amdkfd: Fix error handling for missing PASID in 'kfd_process_device_init_vm'

In the kfd_process_device_init_vm function, a valid error code is now
returned when the associated Process Address Space ID (PASID) is not
present.

If the address space virtual memory (avm) does not have an associated
PASID, the function sets the ret variable to -EINVAL before proceeding
to the error handling section. This ensures that the calling function,
such as kfd_ioctl_acquire_vm, can appropriately handle the error,
thereby preventing any issues during virtual memory initialization.

Fixes the below:
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_process.c:1694 kfd_process_device_init_vm()
warn: missing error code 'ret'

drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_process.c
    1647 int kfd_process_device_init_vm(struct kfd_process_device *pdd,
    1648                                struct file *drm_file)
    1649 {
    ...
    1690
    1691         if (unlikely(!avm->pasid)) {
    1692                 dev_warn(pdd->dev->adev->dev, "WARN: vm %p has no pasid associated",
    1693                                  avm);
--> 1694                 goto err_get_pasid;

ret = -EINVAL?

    1695         }

Fixes: 8544374c ("drm/amdkfd: Have kfd driver use same PASID values from graphic driver")
Reported by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: Xiaogang Chen <xiaogang.chen@amd.com>
Cc: Felix Kuehling <felix.kuehling@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>