fix sparse, checkpatch warnings in OMAP2/3 PRCM/PM code

Fix sparse & checkpatch warnings in OMAP2/3 PRCM & PM code.  This mostly
consists of:

- converting pointer comparisons to integers in form similar to
  (ptr == 0) to the standard idiom (!ptr)

- labeling a few non-static private functions as static

- tagging appropriate integer<->pointer casts with __force

- adding prototypes for *_init() functions in the appropriate header
  files, and getting rid of the corresponding open-coded extern
  prototypes in other C files

- renaming the variable 'sclk' in mach-omap2/clock.c:omap2_get_apll_clkin
  to avoid shadowing an earlier declaration

Clean up checkpatch issues.  This mostly involves:

- converting some asm/ includes to linux/ includes

- cleaning up some whitespace

- getting rid of braces for conditionals with single following statements

Also take care of a few odds and ends, including:

- getting rid of unlikely() and likely() - none of this code is particularly
  fast-path code, so the performance impact seems slim; and some of those
  likely() and unlikely() indicators are probably not as accurate as the
  ARM's branch predictor

- removing some superfluous casts

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