updated gpiolib patchset

This patchset is intended to replace the ones currently in the MM tree:

generic-gpio-gpio_chip-support.patch generic-gpio-gpio_chip-support-fix.patch generic-gpio-gpio_chip-support-gpiolib-locking-simplified.patch avr32-uses-gpio_chip.patch mcp23s08-spi-gpio-expander.patch mcp23s08-spi-gpio-expander-checkpatch-fixes.patch arm-pxa-gpiolib-support.patch arm-pxa-gpiolib-support-make-pxa_gpio_chip-static.patch

Changes since the version in mm include: merging the various fixlets; adding drivers for two I2C based GPIO expanders; and (the main reason for replacement patches vs incremental ones) moving all non-platform code into the new drivers/gpio directory. Also, it now uses a new internal "struct gpio_desc" abstraction -- somewhat visible to the GPIO providers since ARCH_GPIOS_PER_CHIP is now gone. All those changes were posted previously.

Patches in this set are:

- Add empty drivers/gpio directory and kconfig/kbuild support. Before this kicks in, platform support is needed.

- Core gpiolib support. Merges various updates as previously discussed, notably simpler locking, the gpio_desc stuff (from Eric Miao); and moving this from "lib" to "drivers/gpio".

- Documentation/gpio.txt updates.

- AVR32 platform support (at32ap)

- PXA platform support (from Philipp Zabel, essentially unchanged)

- PCF 857x I2C GPIO expander support ... a pretty widely used family of "quasi-bidirectional" GPIOs (8 or 16 bits, many speeds)

- MCP 23S08 SPI GPIO expander support ... with more traditional push/pull outputs and hi-Z inputs

- PCA 9539 I2C GPIO expander support ... a sixteen bit expander using push/pull outputs etc (from Eric Miao)

- Deprecate the older (unused) PCA9539 driver (from Eric Miao)