FPGA: Reduce input size for Shannonization (#1484)

* Reduce input size

* Also update README

Author: shuoniu-intel

DirectProgramming/C++SYCL_FPGA/Tutorials/DesignPatterns/shannonization/README.md

@@ -351,8 +351,8 @@ The following table explains the command-line arguments that can be passed to th
 
 | Argument name | Description               | Default
 |:---           |:---                       |:---
-|`--A`          | Set the size of array A   | 128 for emulation, 131072 for FPGA
-|`--B`          | Set the size of array B   | 256 for emulation, 262144 for FPGA
+|`--A`          | Set the size of array A   | 128 for emulation, 16384 for FPGA
+|`--B`          | Set the size of array B   | 256 for emulation, 32768 for FPGA
 |`--help`       | Print the help message    | N/A
 
 ### On Linux

DirectProgramming/C++SYCL_FPGA/Tutorials/DesignPatterns/shannonization/src/shannonization.cpp

@@ -191,8 +191,8 @@ int main(int argc, char** argv) {
   unsigned int a_size = 128;
   unsigned int b_size = 256;
 #else
-  unsigned int a_size = 131072;
-  unsigned int b_size = 262144;
+  unsigned int a_size = 16384;
+  unsigned int b_size = 32768;
 #endif
   bool need_help = false;