arm64: dts: ti: k3-j784s4-main: Enable refclock output from serdes.

commit 2b2d2a3e749290b7dc34f8803da730177c2bf265 from
git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git



Add property "ti,syscon-pcie-refclk-out" to provide register offsets in
system-controller (SYSCON), which are used to select clock source and
enable ACSPCIe clock buffer output to enable reference clock output.

Signed-off-by: Achal Verma <a-verma1@ti.com>
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>