ARM: OMAP4: board-omap4panda: Register platform device for HDMI audio codec

Add platform device registratation for HDMI audio codec. This is to
be able to transmit audio through the HDMI output featured in Pandaboard
and PandaboardES boards.

Signed-off-by: Ricardo Neri <ricardo.neri@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>