OMAP2+: clock: autoidle as many clocks as possible if CONFIG_OMAP_RESET_CLOCKS

Attempt to enable autoidle for as many clocks as possible in the
OMAP2+-common CONFIG_OMAP_RESET_CLOCKS code.  Currently, this only
enables DPLL autoidle for OMAP3/4 DPLLs; but future patches will
enable autoidle for other clocks and the OMAP2 DPLL/APLLs.

In the long run, we should probably get rid of
CONFIG_OMAP_RESET_CLOCKS, and unconditionally run the code that it
selects.  Otherwise, the state of the clock tree won't match the
hardware state - this could result in clocks being enabled or disabled
unpredictably.

Based on a patch by Rajendra Nayak <rnayak@ti.com> that did this in
the pm34xx.c/pm44xx.c code.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Rajendra Nayak <rnayak@ti.com>