octeontx2-pf: Avoid adding dcbnl_ops for LBK and SDP vf

Priority flow control is not supported for LBK and SDP vf. This patch
adds support to not add dcbnl_ops for LBK and SDP vf.

Fixes: 8e67558177f8 ("octeontx2-pf: PFC config support with DCBx")
Signed-off-by: Suman Ghosh <sumang@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250519072658.2960851-1-sumang@marvell.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>