HTCHERALD: MMC, I2C, HTCPLD, SPI, TSC2046

This change adds in MMC and I2C support to the HTC Herald board, as well
as adding the HTCPLD driver for the PLD used on this phone.  It also
adds in the gpio-keys entries for the front directional keys and
selector and the cursor keys on the slide-out keyboard, and gpio-leds
support for the LEDs attached to the htcpld.

Additionally, SPI bus support (using the spi100k driver) and
touchscreen support (using the ads7846 driver) were added.
Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>