OMAP3 PM: convert open-coded iterator to use pwrdm_for_each_clkdm()

OMAP3 PM: convert open-coded iterator to use pwrdm_for_each_clkdm()

Convert iterators of the list of clockdomains in a powerdomain to use
pwrdm_for_each_clkdm(), rather than an open-coded for-loop.

This also fixes a bug when the D2D clockdomain is added to the 3430ES2
chip.  The open-coded for-loop tested for a NULL pointer in pwrdm_clkdms[]
to determine when to end the loop.  This causes the iterator to fall
off the end of the array when the powerdomain contains the maximum number
of clockdomains per powerdomain (currently 3).

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