ARM: OMAP2+: hwmod: reorganize and document the setup process

Reorganize the code involved in initializing and configuring an IP
block to make it easier to read and maintain.  This involves improving
documentation, splitting some large functions up into smaller ones to
better conform with Documentation/CodingStyle, and removing some
unnecessary code.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoît Cousson <b-cousson@ti.com>