IB/rdmavt: Correct comments in rdmavt_qp.h header

IB/rdmavt: Correct comments in rdmavt_qp.h header

Comments need to be with the definition of rvt_restart_sge().

Other comments were duplicated in sw/rdmavt/rc.c and were removed.

Fixes: 7f3cbdda18f8 ("IB/hfi: Move RC functions into a header file")
Link: https://lore.kernel.org/r/20191219211934.58387.88014.stgit@awfm-01.aw.intel.com
Reviewed-by: Kaike Wan <kaike.wan@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>