eth: bnxt: remove most dependencies on RTNL

Only devlink and sriov paths are grabbing rtnl explicitly. The rest is
covered by netdev instance lock which the core now grabs, so there is
no need to manage rtnl in most places anymore.

On the core side we can now try to drop rtnl in some places
(do_setlink for example) for the drivers that signal non-rtnl
mode (TBD).

Boot-tested and with `ethtool -L eth1 combined 24` to trigger reset.

Cc: Saeed Mahameed <saeed@kernel.org>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250305163732.2766420-15-sdf@fomichev.me
Signed-off-by: Jakub Kicinski <kuba@kernel.org>