FPGA: Correct performance testing date in matmul

Author: yuguen

DirectProgramming/C++SYCL_FPGA/ReferenceDesigns/matmul/README.md

@@ -54,7 +54,7 @@ You can also find more information about [troubleshooting build errors](/DirectP
 
 ### Performance
 
-Performance results are based on testing as of March 6, 2023.
+Performance results are based on testing as of May 14, 2024.
 
 > **Note**: Refer to the [Performance Disclaimers](/DirectProgramming/C++SYCL_FPGA/README.md#performance-disclaimers) section for important performance information.