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>
diff --git a/drivers/serial/8250.h b/drivers/serial/8250.h
index 5202603..6e19ea3 100644
--- a/drivers/serial/8250.h
+++ b/drivers/serial/8250.h
@@ -25,6 +25,7 @@
 	unsigned char io_type;
 	unsigned char *iomem_base;
 	unsigned short iomem_reg_shift;
+	unsigned long irqflags;
 };
 
 /*