serial: 8250: add IRQ trigger support

There is currently no provision for passing IRQ trigger flags for
serial IRQs with triggering requirements (such as GPIO IRQs)

This patch adds irqflags to plat_serial8250_port that can be passed
from board file to reqest_irq() of 8250 driver

Changes are backward compatible with boards passing UPF_SHARE_IRQ flag

Tested on Zoom2 board that has IRQF_TRIGGER_RISING requirement for 8250 irq

[Moved new flag to end to fix bugs in the original with the old_serial array
	-- Alan]

Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/serial_8250.h

@@ -22,6 +22,7 @@ struct plat_serial8250_port {
 	void __iomem	*membase;	/* ioremap cookie or NULL */
 	resource_size_t	mapbase;	/* resource base */
 	unsigned int	irq;		/* interrupt number */
+	unsigned long	irqflags;	/* request_irq flags */
 	unsigned int	uartclk;	/* UART clock rate */
 	void            *private_data;
 	unsigned char	regshift;	/* register shift */

include/linux/serial_core.h

@@ -265,6 +265,7 @@ struct uart_port {
 	unsigned int		(*serial_in)(struct uart_port *, int);
 	void			(*serial_out)(struct uart_port *, int, int);
 	unsigned int		irq;			/* irq number */
+	unsigned long		irqflags;		/* irq flags  */
 	unsigned int		uartclk;		/* base uart clock */
 	unsigned int		fifosize;		/* tx fifo size */
 	unsigned char		x_char;			/* xon/xoff char */