drm/amdkfd: Cleanup vm process info if init vm failed

If acquire_vm failed when initializing KFD vm, set vm->process_info to
NULL and free process info, otherwise, the future acquire_vm will
always fail as vm->process_info is not NULL.

Pass avm as parameter to remove the duplicate code.

Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>