ARM: dts: imx6: remove config space from PCIe controller ranges property

This has been moved to the reg property where it belongs for quite some
time. The range has been unused by the kernel since then and with kernel
4.4 it's flagged as an unparsable range, as it does not comply to the
PCI ranges DT binding. Fix this by removing the superfluous range.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>