x86, early_serial_console: Remove unused macro XMTRDY

There is no write to serial routine, no need for XMTRDY macro.
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
Link: http://lkml.kernel.org/r/1420034191-20721-1-git-send-email-kuleshovmail@gmail.comSigned-off-by: Borislav Petkov <bp@suse.de>

arch/x86/boot/early_serial_console.c

@@ -2,8 +2,6 @@
 
 #define DEFAULT_SERIAL_PORT 0x3f8 /* ttyS0 */
 
-#define XMTRDY          0x20
-
 #define DLAB		0x80
 
 #define TXR             0       /*  Transmit register (WRITE) */