tty/serial: Migrate amba-pl01* 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: Russell King <[e-mail]>
Signed-off-by: Dmitry Safonov <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/amba-pl010.c

···
  * and hooked into this driver.
  */
 
-#if defined(CONFIG_SERIAL_AMBA_PL010_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
-#define SUPPORT_SYSRQ
-#endif
-
 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
···
 	uap->port.iotype = UPIO_MEM;
 	uap->port.irq = dev->irq[0];
 	uap->port.fifosize = 16;
+	uap->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_AMBA_PL010_CONSOLE);
 	uap->port.ops = &amba_pl010_pops;
 	uap->port.flags = UPF_BOOT_AUTOCONF;
 	uap->port.line = i;

drivers/tty/serial/amba-pl011.c

···
  * and hooked into this driver.
  */
 
-
-#if defined(CONFIG_SERIAL_AMBA_PL011_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
-#define SUPPORT_SYSRQ
-#endif
-
 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
···
 	uap->port.mapbase = mmiobase->start;
 	uap->port.membase = base;
 	uap->port.fifosize = uap->fifosize;
+	uap->port.has_sysrq = IS_ENABLED(CONFIG_SERIAL_AMBA_PL011_CONSOLE);
 	uap->port.flags = UPF_BOOT_AUTOCONF;
 	uap->port.line = index;