ARM: OMAP3: clock: add support for dpll4_set_rate_and_parent

Expand the support of omap4 per-dpll to provide set_rate_and_parent.
This is required for proper behavior of clk_change_rate with
determine_rate support.

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