drivers: pci: ignore disabled devices

PCI devices may be disabled in the device tree. Devices which are probed
by the device tree handle the "status" property and are skipped if
disabled. Devices which are probed by the PCI enumeration don't check
that property. Fix it.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Alex Marginean <alexandru.marginean@nxp.com>
Tested-by: Alex Marginean <alexandru.marginean@nxp.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>