staging: csr: remove odd pointer typedefs

No one was using CsrPtrdiff or CsrUintptr, but CsrIntptr is used in one
place, so replace that with ptrdiff_t.  Odds are all it really wants is
a void * there, but hey, I'll play along for now.

Cc: Mikko Virkkilä <mikko.virkkila@bluegiga.com>
Cc: Lauri Hintsala <Lauri.Hintsala@bluegiga.com>
Cc: Riku Mettälä <riku.mettala@bluegiga.com>
Cc: Veli-Pekka Peltola <veli-pekka.peltola@bluegiga.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>