tty/serial: Migrate qcom_geni_serial to use has_sysrq

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: Andy Gross <agross@kernel.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: linux-arm-msm@vger.kernel.org
Signed-off-by: Dmitry Safonov <dima@arista.com>
Link: https://lore.kernel.org/r/20191213000657.931618-36-dima@arista.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/qcom_geni_serial.c

 // SPDX-License-Identifier: GPL-2.0
 // Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
 
-#if defined(CONFIG_SERIAL_QCOM_GENI_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
-# define SUPPORT_SYSRQ
-#endif
-
 #include <linux/clk.h>
 #include <linux/console.h>
 #include <linux/io.h>
@@ -1308,6 +1304,7 @@ static int qcom_geni_serial_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return irq;
 	uport->irq = irq;
+	uport->has_sysrq = IS_ENABLED(CONFIG_SERIAL_QCOM_GENI_CONSOLE);
 
 	irq_set_status_flags(uport->irq, IRQ_NOAUTOEN);
 	ret = devm_request_irq(uport->dev, uport->irq, qcom_geni_serial_isr,