IB/hfi1: Add PSM2 user space header to header_install

When the hfi1 driver was added a user space header file (hfi1_user.h) was added
to be shared between PSM2 and the driver.  However, the file was not added to
the header install.  Add it now.

Fixes: d4ab3470 ("IB/core: Add core header changes needed for OPA")
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>