arm64: dts: ti: k3-am64-main: Add ICSSG IEP nodes

arm64: dts: ti: k3-am64-main: Add ICSSG IEP nodes

The ICSSG IP on AM64x SoCs have two Industrial Ethernet Peripherals (IEPs)
to manage/generate Industrial Ethernet functions such as time stamping.
Each IEP sub-module is sourced from an internal clock mux that can be
derived from either of the IP instance's ICSSG_IEP_GCLK or from another
internal ICSSG CORE_CLK mux. Add both the IEP nodes for both the ICSSG
instances. The IEP clock is currently configured to be derived
indirectly from the ICSSG_ICLK running at 250 MHz.

Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Link: https://lore.kernel.org/r/20240215103036.2825096-2-danishanwar@ti.com
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>