OMAP: hwmod data: add class for IVA hwmods

Add a new hwmod class for IVA devices.  To be used when hwmods
are created for IVA2 on OMAP3.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Benoît Cousson <b-cousson@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>