Revert kelvin_hello_world printf

Reason to revert: break DV

Change-Id: If1e9e956fca30d473be68d11e8db813926c376a1

sw/device/tests/kelvin/kelvin_hello_world.c

diff --git a/sw/device/tests/kelvin/kelvin_hello_world.c b/sw/device/tests/kelvin/kelvin_hello_world.c
index f3b2aaf..7109422 100644
--- a/sw/device/tests/kelvin/kelvin_hello_world.c
+++ b/sw/device/tests/kelvin/kelvin_hello_world.c
@@ -18,14 +18,12 @@
 
 #include <stddef.h>
 #include <stdint.h>
-#include <stdio.h>
 
 const uint32_t kDataInput = 0x100000;
 const uint32_t kDataSize = 0x1000;
 
 int main(int argc, char *argv[]) {
   uint32_t *data = (uint32_t *)kDataInput;
-  printf("hello world!!\n");
   for (uint32_t i = 0; i < kDataSize / sizeof(uint32_t); ++i) {
     data[i] += 1;
   }