ARM: OMAP: Remove unused platform devices, v3

This patch removes old platform devices. Alsa should now
be using the ASoC driver. For boards not yet using ASoC,
please see sound/soc/omap/osk5912.c.

Add dummy aic23_power_up and aic23_power_down functions for 770
to keep things compiling.

Remove references to omap_gpio_switch, and unused h2_nand_dev_ready
function.

This patch is based on an earlier patch by Arun KS.

Cc: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Arun KS <arunks@mistralsolutions.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>