omap1: amsdelta: defconfig updates

The patch provides the following ams_delta_defconfig updates:
- explicitly select preemptable RCU,
- replace outdated CONFIG_LBD and CONFIG_LSF options with CONFIG_LBDAF,
- activate support for LCD contrast setting (new in 2.6.34),
- turn off verbose bug reporting for smaller kernel.

Created and tested against linux-2.6.34-rc3.

Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Tony Lindgren <tony@atomide.com>