PCI: aardvark: Disable link training when unbinding driver

Disable link training circuit in driver unbind sequence. We want to
leave link training in the same state as it was before the driver was
probed.

Link: https://lore.kernel.org/r/20211130172913.9727-11-kabel@kernel.org


Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>