PCI: aardvark: Fix memory leak in driver unbind

Free config space for emulated root bridge when unbinding driver to fix
memory leak. Do it after disabling and masking all interrupts, since
aardvark interrupt handler accesses config space of emulated root
bridge.

Link: https://lore.kernel.org/r/20211130172913.9727-9-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>