omap1: Add omap1_defconfig

The omap1_defconfig this should be eventually usable for booting
all omap1 machines. Generated based on:

$ grep ARCH_OMAP1=y arch/arm/configs/* | cut -d: -f1 | xargs cat | \
     sort | uniq >> arch/arm/configs/omap1_defconfig

Then change few things manually, like use Nokia 770 CONFIG_CMDLINE
as it does not allow setting it in the bootloader.

Finally ran make savedefconfig on it.

Signed-off-by: Tony Lindgren <tony@atomide.com>