ARM: 8278/1: sa1100: split irq handling for low GPIOs

Low GPIO pins use an interrupt in SC interrupts space. However it's
possible to handle them as if all the GPIO interrupts are instead tied
to single GPIO handler, which later decodes GEDR register and
chain-calls next IRQ handler. So split first 11 interrupts into system
part (IRQ_GPIO0_SC - IRQ_GPIO10_SC) which work exactly like the rest of
system controller interrupts and real GPIO interrupts
(IRQ_GPIO0..IRQ_GPIO10). A single handler sa1100_gpio_handler then
decodes and calls next handler.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/drivers/gpio/gpio-sa1100.c b/drivers/gpio/gpio-sa1100.c
index a90be34..5b5d3c7 100644
--- a/drivers/gpio/gpio-sa1100.c
+++ b/drivers/gpio/gpio-sa1100.c
@@ -50,7 +50,7 @@
 
 static int sa1100_to_irq(struct gpio_chip *chip, unsigned offset)
 {
-	return offset < 11 ? (IRQ_GPIO0 + offset) : (IRQ_GPIO11 - 11 + offset);
+	return IRQ_GPIO0 + offset;
 }
 
 static struct gpio_chip sa1100_gpio_chip = {