dt-bindings: pci: ti,j721e: Fix "ti,syscon-pcie-ctrl" to take argument

Fix binding documentation of "ti,syscon-pcie-ctrl" to take phandle with
argument. The argument is the register offset within "syscon" used to
configure PCIe controller. This change is as discussed in [1]

[1] -> http://lore.kernel.org/r/CAL_JsqKiUcO76bo1GoepWM1TusJWoty_BRy2hFSgtEVMqtrvvQ@mail.gmail.com

Link: https://lore.kernel.org/r/20201210124917.24185-2-kishon@ti.com


Fixes: 431b53b8 ("dt-bindings: PCI: Add host mode dt-bindings for TI's J721E SoC")
Fixes: 45b39e92 ("dt-bindings: PCI: Add EP mode dt-bindings for TI's J721E SoC")
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>