Blackfin Serial Driver: Fix bug - kernel hangs when accessing uart 0 on bf537 when booting u-boot and linux on uart 1

Wait only when this UART is enabled.
http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=3995

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

drivers/serial/bfin_5xx.c

@@ -806,10 +806,6 @@ bfin_serial_set_termios(struct uart_port *port, struct ktermios *termios,
 
 	UART_SET_ANOMALY_THRESHOLD(uart, USEC_PER_SEC / baud * 15);
 
-	do {
-		lsr = UART_GET_LSR(uart);
-	} while (!(lsr & TEMT));
-
 	/* Disable UART */
 	ier = UART_GET_IER(uart);
 #ifdef CONFIG_BF54x