ARM: OMAP: Enable 34xx autoidle for clocks and plls

Enable autoidle for interface clocks and plls. Also automatic
control of external oscillator through sys_clkreq is enabled.

In the long term, proper solution is to generalize
omap3_dpll_allow_idle, omap3_dpll_deny_idle,
omap3_dpll_autoidle_read and call it for each clock on init.

Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>