mach-omap2: fix sparse warnings, some style issues for OMAP2 builds

This cleans up remaining sparse warnings for OMAP2 builds and fixes a
few CodingStyle issues.  This involves:

- removing casts where they don't belong,

- adding casts where they should be,

- marking internal functions as static,

- fixing some indentation in board-2430sdp-flash.c.

Patch should cause no change in kernel behavior.

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