RDMA/providers: Fix return value when QP type isn't supported

The proper return code is "-EOPNOTSUPP" when the requested QP type is
not supported by the provider.

Link: https://lore.kernel.org/r/20200130082049.463-1-kamalheib1@gmail.com


Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>