You at least need to add the .java extension to the file name in this line:
javac -cp /home/manish.yadav/Desktop/JCuda-All-0.3.2-bin-linux-x86_64 EnumDevices
From the official faq:
Class names, ‘HelloWorldApp’, are only accepted if annotation processing is explicitly requested
If you receive this error, you forgot to include the .java suffix when compiling the program. Remember, the command is javac HelloWorldApp.java not javac HelloWorldApp.
Also, in your second javac-example, (in which you actually included .java) you need to include the all required .jar-files needed for compilation.