[ARM] 4739/1: at91sam9263: make gpio bank C and D irqs work

On the at91sam9263, IRQs for GPIO banks C and D don't currently work.
This is because banks C, D, and E share one clock and toplevel IRQ, but
the AT91 code setting up and handling GPIO IRQs expects no sharing.
This patch:

 - Fixes GPIO IRQ setup and handling to cope with GPIO banks that are
   shared like on sam9263 chips, by setting up a list of those banks
   and making the IRQ dispatching logic scan that list.

 - Precomputes the address of each bank's registers, saving it with
   other per-bank data so that it no longer needs to be constantly
   recomputed during IRQs and other GPIO operations.  That shrinks
   hot-path code, while helping the GPIO bank irq updates.

 - Fixes a minor bug where IRQ_TYPE_NONE was wrongly rejected (it just
   means "use the default", which is "both edges" here).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-at91/generic.h

@@ -47,6 +47,9 @@ extern void at91_irq_resume(void);
 #define AT91RM9200_BGA		4	/* AT91RM9200 BGA package has 4 banks */
 
 struct at91_gpio_bank {
+	unsigned chipbase;		/* bank's first GPIO number */
+	void __iomem *regbase;		/* base of register bank */
+	struct at91_gpio_bank *next;	/* bank sharing same IRQ/clock/... */
 	unsigned short id;		/* peripheral ID */
 	unsigned long offset;		/* offset from system peripheral base */
 	struct clk *clock;		/* associated clock */