feat: bsp: qemu-riscv64: using klibc API for printf

bsp/qemu-virt64-riscv/applications/main.c

@@ -9,12 +9,11 @@
 
 #include <rtthread.h>
 #include <rthw.h>
-#include <stdio.h>
 #include <string.h>
 
 int main(void)
 {
-    printf("Hello RISC-V\n");
+    rt_kprintf("Hello RISC-V\n");
 
     return 0;
 }