OMAP3 PRCM: add DPLL1-5 powerdomains, clockdomains

Each DPLL exists in its own powerdomain (cf 34xx TRM figure 4-18) and
clockdomain; so, create powerdomain and clockdomain structures for them.
These are used in a following patch for DPLL-related clocks.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>