On OMAP various clock nodes (dpll's, mx post dividers, interface clocks)
support hardware level autogating which can be controlled from
software.
Support such functionality by adding two new function pointer
allow_idle and deny_idle in the clkops structure.

These function pointers can be populated for any clock
node which supports hardware level autogating.

Also add 2 new functions (omap_clk_enable_autoidle_all and
omap_clk_disable_autoidle_all) which can be called from
architecture specific PM core code, if hardware level
autogating (for all supported clock nodes) is to be
enabled or disabled.
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
[paul@pwsan.com: use spinlock rather than mutex due to race; renamed functions;
 functions now return ints]
Signed-off-by: Paul Walmsley <paul@pwsan.com>