i40iw: fix spelling mistake: "allloc_buf" -> "alloc_buf"

Trivial fix to spelling mistake in i40iw_debug  message and
also split up a couple of lines that are too long and cause
checkpatch warnings

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>