samples: net: zperf: Enable i226 config with Intel Alderlake

The Zperf sample application was chosen to demonstrate basic network
functionality and high-performance use cases. This application serves
as a reference for users who wish to enable other network sample
applications.

In addition to the essential configurations for the Intel i226 Ethernet
controller, stack-specific configurations were added to ensure stability
under heavy network loads. These configurations include adjustments to
buffer sizes, interrupt handling, and DMA descriptor management.

Signed-off-by: Vijayakannan Ayyathurai <vijayakannan.ayyathurai@intel.com>