IB/hfi1: fix spelling mistake: "Maximim" -> "Maximum"

Trivial fix to spelling mistake in pr_warn_ratelimited warning message

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>