omap2 clock: convert remaining clksel clocks to use omap2_clksel_recalc

This completes the transition to struct clksel/clksel_rate by converting the
remaining clksel clocks to call omap2_clksel_recalc() on rate recalculation.
Also remove RATE_FIXED from some clocks that can now recalculate their own
rates correctly via clksel.

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