gpiolib: avr32 at32ap platform support

Teach AVR32 to use the "GPIO Library" when exposing its GPIOs, so that signals
on external chips (like GPIO expanders) can easily be used.

This mostly reorganizes some existing logic, with two minor changes in
behavior:

 - The PSR registers are used instead of the previous "gpio_mask" values,
   matching AT91 behavior and removing some duplication between that role
   and that of "pinmux_mask".

 - NR_IRQs grew to acommodate a bank of external GPIOs.  Eventually this
   number should probably become a board-specific config option.

There's a debugfs dump of status for the built-in GPIOs, showing which pins
have deglitching, pullups, or open drain drive enabled, as well as the ID
string used when requesting each IRQ.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Eric Miao <eric.miao@marvell.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Philipp Zabel <philipp.zabel@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/avr32/Kconfig b/arch/avr32/Kconfig
index c816f29..28e0caf 100644
--- a/arch/avr32/Kconfig
+++ b/arch/avr32/Kconfig
@@ -82,6 +82,7 @@
 	select SUBARCH_AVR32B
 	select MMU
 	select PERFORMANCE_COUNTERS
+	select HAVE_GPIO_LIB
 
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 # CPU types