OMAP2+: defconfig: modularize bluetooth, audio and WLAN

In working towards a smaller default kernel, only devices used for
early boot should be built in.  Toward that end, build the following
as modules by default:

- bluetooth
- audio: ALSA, ASoC
- WLAN

Uncompressed kernel size comparison:

Before:
   text	   data	    bss	    dec	    hex	filename
6557576	 465088	5616024	12638688	 c0d9e0	vmlinux

After:
   text	   data	    bss	    dec	    hex	filename
5616572	 436448	5610800	11663820	 b1f9cc	vmlinux

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>