ARMV7: Add support for TI OMAP4430 SDP

OMAP4430 SDP is a reference board based on OMAP4430, an ARMV7 Cortex A9 CPU

This patch adds basic support for booting the board. It includes i2c and mmc
support. It assumes U-boot is loaded to SDRAM with the help of another small
bootloader (x-load) running from SRAM. U-boot currently relies on x-load for
clock, mux, and SDRAM initialization

Signed-off-by: Aneesh V <aneesh@ti.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>