ARM: OMAP3: clock: add new rate changing logic support for noncore DPLLs

Currently, DPLL code hides the re-parenting within its internals, which
is wrong. This needs to be exposed to the common clock code via
determine_rate and set_rate_and_parent APIs. This patch adds support
for these, which will be taken into use in the following patches.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>