IB/hfi1: Use a common pad buffer for 9B and 16B packets

IB/hfi1: Use a common pad buffer for 9B and 16B packets

There is no reason for a different pad buffer for the two
packet types.

Expand the current buffer allocation to allow for both
packet types.

Fixes: f8195f3b14a0 ("IB/hfi1: Eliminate allocation while atomic")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Kaike Wan <kaike.wan@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Link: https://lore.kernel.org/r/20191004204934.26838.13099.stgit@awfm-01.aw.intel.com
Signed-off-by: Doug Ledford <dledford@redhat.com>