ARM: dts: dra7-evm: Move pcie RC node to common file

Move the pcie_rc node to common file so that it can be
used by dra76-evm as well.

Signed-off-by: Ravikumar Kattekola <rk@ti.com>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>