Convert the OMAP clock code's _omap2_module_wait_ready() to use
SoC-independent CM functions that are provided by the CM code, rather
than using a deprecated function from mach-omap2/prcm.c.

This facilitates the future conversion of the CM code to a driver, and
also removes a mach-omap2/prcm.c user.  mach-omap2/prcm.c will be removed
by a subsequent patch.

Some modules have IDLEST registers that aren't in the CM module, such
as the AM3517 IDLEST bits.  So we also need a fallback function for
these non-CM odd cases.  Create a temporary one in mach-omap2/clock.c,
intended to exist until the SCM drivers are ready.
Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Tested-by: NVaibhav Hiremath <hvaibhav@ti.com>

There are several CM operations which behave similarly across OMAP2+
SoCs, but which have slight differences in their underlying
implementations.

This patch creates the support code for this function pointer
registration process.  No function pointers are included yet, but a
subsequent patch will create these for the module IDLEST registers.

This patch allows other code to use CM-provided data and operations
without needing to know which SoC is currently in use.  A further
description of the concept is provided in the patch entitled
"ARM: OMAP2+: PRM: prepare for use of prm_ll_data function pointers".
Signed-off-by: NPaul Walmsley <paul@pwsan.com>