Fix GCC format-security errors and convert sprintfs.

With format-security errors turned on, GCC picks up the use of sprintf with
a format parameter not being a string literal.

Simple uses of sprintf are also converted to use strcpy.

Signed-off-by: Ben Whitten <ben.whitten@gmail.com>
Acked-by: Wolfgang Denk <wd@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>

scripts/kconfig/mconf.c

@@ -379,7 +379,7 @@ static void update_text(char *buf, size_t start, size_t end, void *_data)
 				data->targets[k] = pos->target;
 				k++;
 			} else {
-				sprintf(header, "   ");
+				strcpy(header, "   ");
 			}
 
 			memcpy(buf + pos->offset, header, sizeof(header) - 1);