net: devlink: convert reload command to take implicit devlink->lock

Convert reload command to behave the same way as the rest of the
commands and let if be called with devlink->lock held. Remove the
temporary devl_lock taking from drivers. As the DEVLINK_NL_FLAG_NO_LOCK
flag is no longer used, remove it alongside.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>