devlink: Add 'total_vfs' generic device param

devlink: Add 'total_vfs' generic device param

NICs are typically configured with total_vfs=0, forcing users to rely
on external tools to enable SR-IOV (a widely used and essential feature).

Add total_vfs parameter to devlink for SR-IOV max VF configurability.
Enables standard kernel tools to manage SR-IOV, addressing the need for
flexible VF configuration.

Signed-off-by: Vlad Dumitrescu <vdumitrescu@nvidia.com>
Tested-by: Kamal Heib <kheib@redhat.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250907012953.301746-2-saeed@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>