fix: function declaration

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

cores/arduino/itoa.c

@@ -111,7 +111,7 @@ char *itoa(int value, char *string, int radix)
   return ltoa(value, string, radix) ;
 }
 
-char *utoa(unsigned int value, char *string, int radix)
+char *utoa(unsigned value, char *string, int radix)
 {
   return ultoa(value, string, radix) ;
 }