IB/hf1: Remove DMA mapping code

The hfi1 DMA mapping code has never been built in any upstream kernel.
Hence remove it.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Dennis Dalessandro <dennis.dalessandro@intel.com>
Cc: Dean Luick <dean.luick@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>