cxl: Don't remove AFUs/vPHBs in cxl_reset

If the driver doesn't participate in EEH, the AFUs will be removed
by cxl_remove, which will be invoked by EEH.

If the driver does particpate in EEH, the vPHB needs to stick around
so that the it can particpate.

In both cases, we shouldn't remove the AFU/vPHB.

Reviewed-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>