Kernel: PCIe: PCIe_End_Point: Update link for extension cable

Since the extension cable for connecting two PCIe connectors is no
longer available with Adex Electronics, update the link to point to
an equivalent cable available with DigiKey.

Signed-off-by: Siddharth Vadapalli <[email protected]>

Author: Siddharth-Vadapalli-at-TI

source/linux/Foundational_Components/Kernel/Kernel_Drivers/PCIe/PCIe_End_Point.rst

@@ -155,7 +155,7 @@ PCIe End Point
 
 .. Image:: /images/Pcie_ep_cable.jpg
 
-This cable can be obtained from Adex Electronics (https://www.adexelec.com).
+An equivalent cable can be obtained from DigiKey (https://www.digikey.com/en/products/detail/3m/8kj2-0743-0250/5128345).
 
 .. ifconfig:: CONFIG_part_family in ('General_family')