omap3: update omap3_defconfig

- Update the omap3_defconfig to sync up with the generated .config
- Increase CONFIG_LOG_BUF_SHIFT to 16 to allow the entire
  boot log to be captured
  (useful when using boot time tracer, for example)

Signed-off-by: Anand Gadiyar <gadiyar@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>