IB/hfi1: Remove unused sc_drop and sdma_all_idle

sc_drop() and sdma_all_idle() were both added in 2015's commit
77241056 ("IB/hfi1: add driver files") but have remained unused.

Remove them.

Link: https://patch.msgid.link/r/20250505205419.88131-1-linux@treblig.org


Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>