[SERIAL] Fix a problem with 8250 UARTs on PPC

Patch from Tom Rini.

If we don't change the divisor, we don't want to change what we claim
as the uart clock either.  Without this I don't get a usable serial
console on my Motorola Sandpoint.

drivers/serial/8250.c

@@ -530,10 +530,10 @@ static void autoconfig_16550a(struct uart_8250_port *up)
 			status1 |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */
 			serial_outp(up, 0x04, status1);
 			serial_outp(up, UART_LCR, 0);
+			up->port.uartclk = 921600*16;
 #endif
 
 			up->port.type = PORT_NS16550A;
-			up->port.uartclk = 921600*16;
 			return;
 		}
 	}