HACK: OMAP: DSS2: clk hack for OMAP2/3

The HWMOD data for OMAP2 and 3 are currently not up to date regarding
DSS (OMAP4 HWMOD data is fine). This patch makes the DSS driver to get
the opt clocks needed for OMAP2/3 with the old clock names, thus
allowing DSS driver to use runtime PM.

The HWMOD databases should be fixes ASAP, and this patch can be reverted
after that.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>