Blackfin: recurse with early serial initcode

Make sure we recurse through serial_putc() rather than bang on the UART
transmit register directly to avoid hardware overflows when using \n.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

cpu/blackfin/initcode.c

@@ -92,7 +92,7 @@ static inline void serial_putc(char c)
 		return;
 
 	if (c == '\n')
-		*pUART_THR = '\r';
+		serial_putc('\r');
 
 	*pUART_THR = c;