IB/hfi1: Fix resource release in context allocation

Correct resource free in allocate_ctxt() function.
When context creation fails allocated resources are properly
released and pointer in receive context data table is set back
to NULL.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jakub Pawlak <jakub.pawlak@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>