m68knommu: Fix MCFUART_TXFIFOSIZE for m548x.

Serial lines on the MCF548x have really big fifos : 512 bytes.
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Signed-off-by: Greg Ungerer <gerg@uclinux.org>

arch/m68k/include/asm/mcfuart.h

@@ -217,7 +217,9 @@ struct mcf_platform_uart {
 #define	MCFUART_URF_RXS		0xc0		/* Receiver status */
 #endif
 
-#if defined(CONFIG_M5272)
+#if defined(CONFIG_M548x)
+#define MCFUART_TXFIFOSIZE	512
+#elif defined(CONFIG_M5272)
 #define MCFUART_TXFIFOSIZE	25
 #else
 #define MCFUART_TXFIFOSIZE	1