OMAP2/3 clock: encode target IDLEST bits and clean omap2_clk_wait_ready()

OMAP2/3 clock: encode target IDLEST bits and clean omap2_clk_wait_ready()

For each OMAP module that has a target IDLEST bit, add the appropriate
bits to the clock tree on both the module interface clock and the appropriate
functional clock.  Add a new clock bit, "WAIT_READY", that indicates that
the clock code must wait for the clock's module to come out of idle after
both the target functional clock and interface clocks are enabled.  Fix
some clock flag comments while there to indicate that clocks marked
as "3430ES2" clocks also are valid for later 3430 revisions.

Several OMAP3xxx clocks must be split into platform-specific variants,
since some early silicon revisions do not have target idle state bits
available. DSS, HSOTGUSB, and SSI clocks are affected.  In the future, it
would be ideal to #ifdef out those clocks for kernels that don't need to
run on 3430ES1 chips to save memory.

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