pci_iounmap(): Fix MMIO mapping leak

pci_iounmap(): Fix MMIO mapping leak

The #ifdef ARCH_HAS_GENERIC_IOPORT_MAP accidentally also guards iounmap(),
which means MMIO mappings are leaked.

Move the guard so we call iounmap() for MMIO mappings.

Fixes: 316e8d79a095 ("pci_iounmap'2: Electric Boogaloo: try to make sense of it all")
Link: https://lore.kernel.org/r/20240131090023.12331-2-pstanner@redhat.com
Reported-by: Danilo Krummrich <dakr@redhat.com>
Suggested-by: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: <stable@vger.kernel.org> # v5.15+