ARM: add tuna_defconfig

Change-Id: I025a007a8d6baf495c920f1a29dbf7dd5c94b767
Signed-off-by: Erik Gilling <konkers@android.com>
ARM: tuna: add tuna board file and config

Signed-off-by: Brian Swetland <swetland@google.com>

Conflicts:
	arch/arm/mach-omap2/Makefile