Don't zero the stats before they are read out.

MFC after: 3 days


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273925 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Fix the build of non-FDT systems by moving the gpiobusvar.h header outside
the FDT #ifdef.

While here remove a few unused headers.


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273926 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f