ARM: OMAP: hwmod: Fix up hwmod based clkdm accesses

hwmod uses deferencing the clk pointer to acccess the clkdm.
With COMMON clk hwoever this will need to be deferenced through
the clk_hw_omap pointer, so do the necessary changes.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Mike Turquette <mturquette@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>