The SUPPORT_SYSRQ ifdeffery is not nice as:
- May create misunderstanding about sizeof(struct uart_port) between
  different objects
- Prevents moving functions from serial_core.h
- Reduces readability (well, it's ifdeffery - it's hard to follow)
In order to remove SUPPORT_SYSRQ, has_sysrq variable has been added.
Initialise it in driver's probe and remove ifdeffery.
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-41-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  *  Serial driver for TX3927/TX4927/TX4925/TX4938 internal SIO controller
  */
 
-#if defined(CONFIG_SERIAL_TXX9_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
-#define SUPPORT_SYSRQ
-#endif
-
 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
                port.flags      = p->flags;
                port.mapbase    = p->mapbase;
                port.dev        = &dev->dev;
+               port.has_sysrq  = IS_ENABLED(CONFIG_SERIAL_TXX9_CONSOLE);
                ret = serial_txx9_register_port(&port);
                if (ret < 0) {
                        dev_err(&dev->dev, "unable to register port at index %d "