OMAP2/3 clock: Extend find_idlest() to pass back idle state value

Current implementation defines clock idle state indicators based on the
cpu information (cpu_is_omap24xx() or cpu_is_omap34xx()) in a system wide
manner. This patch extends the find_idlest() function in clkops to pass
back the idle state indicator for that clock, thus allowing idle state
indicators to be defined on a per clock basis if required.

This is specifically needed on AM35xx devices as the new IPSS clocks
indicates the idle status (0 is idle, 1 is ready) in a way just
opposite to how its handled in OMAP3 (0 is ready, 1 is idle).

Signed-off-by: Ranjith Lohithakshan <ranjithl@ti.com>
[paul@pwsan.com: updated to apply after commit 98c45457 et seq.]
Signed-off-by: Paul Walmsley <paul@pwsan.com>