ns16550: Fix mem mapped endian check

Do a explicit check for CONFIG_SYS_BIG_ENDIAN and
CONFIG_SYS_LITTLE_ENDIAN to avoid errors on platforms where both
are undefined (x86).
Signed-off-by: NBernhard Messerklinger <bernhard.messerklinger@br-automation.com>
Reviewed-by: NHannes Schmelzer <hannes.schmelzer@br-automation.com>

drivers/serial/ns16550.c

@@ -55,7 +55,7 @@ static inline void serial_out_shift(void *addr, int shift, int value)
 {
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
 	outb(value, (ulong)addr);
-#elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_SYS_BIG_ENDIAN)
+#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_LITTLE_ENDIAN)
 	out_le32(addr, value);
 #elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_BIG_ENDIAN)
 	out_be32(addr, value);
@@ -72,7 +72,7 @@ static inline int serial_in_shift(void *addr, int shift)
 {
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
 	return inb((ulong)addr);
-#elif defined(CONFIG_SYS_NS16550_MEM32) && !defined(CONFIG_SYS_BIG_ENDIAN)
+#elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_LITTLE_ENDIAN)
 	return in_le32(addr);
 #elif defined(CONFIG_SYS_NS16550_MEM32) && defined(CONFIG_SYS_BIG_ENDIAN)
 	return in_be32(addr);