feat(linux): Add XDP and zero copy support documentation for CPSW

ICSSG driver already has documentation support for XDP and
zero copy. Reuse the same for CPSW also by pointing ICSSG
documentation in CPSW.

Signed-off-by: Meghana Malladi <m-malladi@ti.com>

Author: MeghanaMalladiTI

source/linux/Foundational_Components/Kernel/Kernel_Drivers/Network/CPSW-Ethernet.rst

@@ -87,3 +87,8 @@ For further details regarding the TSN features and testing, refer :ref:`tsn_with
    CPSW3g
    CPSWng
    CPSW-TSN
+
+XDP and zero copy
+"""""""""""""""""
+The CPSW Ethernet Subsystem supports XDP and zero copy features similar to PRU-ICSS Ethernet Subsystem.
+For more details refer :ref:`pru_icssg_xdp`.