The PCIe controller is found on all Juno SoC version. However it's not
functional on R0 due to some hardware bug.

In preparation to add Juno R2 support, this patch moves the
pcie-controller defination to base DTS file. It's marked as disabled by
default and is enabled for Juno R1 explicitly.
Acked-by: Liviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>