omap: Remove support for omap2evm

The board support has never been merged for it as noticed
by Russell King <linux@arm.linux.org.uk>. So let's remove the
related dead code.

Cc: linux-fbdev@vger.kernel.org
Cc: alsa-devel@alsa-project.org
Cc: Paul Mundt <lethal@linux-sh.org>
Acked-by: Jarkko Nikula <jhnikula@gmail.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>