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.com


Signed-off-by: Borislav Petkov <bp@suse.de>