staging: wilc1000: Add SDIO/SPI 802.11 driver

This driver is for the wilc1000 which is a single chip IEEE 802.11
b/g/n device.
The driver works together with cfg80211, which is the kernel side of
configuration management for wireless devices because the wilc1000
chipset is fullmac where the MLME is managed in hardware.

The driver worked from kernel version 2.6.38 and being now ported
to several others since then.
A TODO file is included as well in this commit.

Signed-off-by: Johnny Kim <johnny.kim@atmel.com>
Signed-off-by: Rachel Kim <rachel.kim@atmel.com>
Signed-off-by: Dean Lee <dean.lee@atmel.com>
Signed-off-by: Chris Park <chris.park@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>