ARM: omap2plus_defconfig: Add WL1251 and WEXT modules

The Nokia N900 uses a TI WL1251 chip for WiFi. Enable support for it
as a loadable module.

In order to be usable and connect to networks, it needs wireless
extensions, so enable WEXT support in the kernel.

Signed-off-by: Sicelo A. Mhlongo <absicsz@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>