arm/common: Fix arm_nputs.c to avoid mult. up_nputs() definitions

When SEMIHOST_SYSLOG is enabled up_nputs() could be defined twice.

Signed-off-by: Alan C. Assis <acassis@gmail.com>

arch/arm/src/common/arm_nputs.c

@@ -39,6 +39,7 @@
  *
  ****************************************************************************/
 
+#ifndef CONFIG_ARM_SEMIHOSTING_SYSLOG
 void up_nputs(const char *str, size_t len)
 {
   while (len-- > 0 && *str)
@@ -46,3 +47,4 @@ void up_nputs(const char *str, size_t len)
       up_putc(*str++);
     }
 }
+#endif