sif: Compile with kernel 4.4.10

sif: Compile with kernel 4.4.10

* Remove obsolete (dummy) unimplemented fast_reg call impl
  This has changed significantly in 4.4.x and was not
  implemented for older kernels anyway.

* Add ifdefs for new wr struct layout -
  no longer uses union, instead we have to upcast
  to the right type to find the qp/request
  type specific fields

* undefine the mtrr code as the mtrr_del function seems not to be
  made available anymore. The functionality is not used anyway atm.

* Some regressions wrt checkpatch

Signed-off-by: Knut Omang <knut.omang@oracle.com>