[Drbd-dev] fix various asm-generic abuses

[Christoph Hellwig]

This fixes two trivial classes of asm-generic abuse.  First two headers
that are intended for drivers are moved to include/linux, and second
various drivers that incorrectly use asm-generic headers directly are
switched over to use the proper public headers.  There are a few more
asm-generic abuse, but they aren't quite as trivial so they will take
a little more effort to fix.