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.
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-stm32@st-md-mailman.stormreply.com
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-45-dima@arista.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  * Inspired by st-asc.c from STMicroelectronics (c)
  */
 
-#if defined(CONFIG_SERIAL_STM32_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
-#define SUPPORT_SYSRQ
-#endif
-
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/delay.h>
        port->ops       = &stm32_uart_ops;
        port->dev       = &pdev->dev;
        port->fifosize  = stm32port->info->cfg.fifosize;
+       port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_STM32_CONSOLE);
 
        ret = platform_get_irq(pdev, 0);
        if (ret <= 0)