RDMA/hfi1: Fix trivial mis-spelling of 'descriptor'

The word 'descriptor' is misspelled throughout the tree.

Fix it up accordingly:
    decriptors -> descriptors

Link: https://lore.kernel.org/r/20200609124610.3445662-3-kieran.bingham+renesas@ideasonboard.com
Link: https://lore.kernel.org/r/20200609124610.3445662-12-kieran.bingham+renesas@ideasonboard.com
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>