Make device flag in vcopy optional

Signed-off-by: colramos-amd <colramos@amd.com>

sample/vcopy.cpp

@@ -2,6 +2,8 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <math.h>
+#include <iostream>
+using namespace std;
 
 
 #define HIP_ASSERT(x) (assert((x)==hipSuccess))
@@ -19,7 +21,7 @@ __global__ void vecCopy(double *a, double *b, double *c, int n,int stride)
 
 void usage()
 {
-  printf("\nUsage: vcopy [n] [blocksize] [dev]\n\n");
+  printf("\nUsage: vcopy [n] [blocksize] {dev}\n\n");
   exit(1);
   return;
 }
@@ -47,12 +49,13 @@ int main( int argc, char* argv[] )
     int stride = 1;
     int devId = 0;
 
-    if(argc < 4)
+    if(argc < 3)
       usage();
+    if(argc > 3)
+      devId = atoi(argv[3]);
 
     n = atoi(argv[1]);
     blockSize = atoi(argv[2]);
-    devId = atoi(argv[3]);
 
     int numGpuDevices;
     HIP_ASSERT(hipGetDeviceCount(&numGpuDevices));