omap3: Add support for flash on 3430SDP board

This patch adds support for flashes on 3430SDP boards. All three
NAND, NOR and OneNAND are supported. I have tested it on
3430SDP (ES2 and ES3.1).

This patch can be treated as an example to "how to utilize":
'gpmc-nand.c' and 'board-sdp-flash.c'.

Similar patches can be created for 2430sdp and 3630sdp or any other
similar board.

Signed-off-by: Vimal Singh <vimalsingh@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>