netdevice.h: fix all kernel-doc and Sphinx warnings

Eliminate all kernel-doc and Sphinx warnings in
<linux/netdevice.h>.  Fixes these warnings:

../include/linux/netdevice.h:2100: warning: Function parameter or member 'gso_partial_features' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'l3mdev_ops' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'xfrmdev_ops' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'tlsdev_ops' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'name_assign_type' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'ieee802154_ptr' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'mpls_ptr' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'xdp_prog' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'gro_flush_timeout' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'xdp_bulkq' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'xps_cpus_map' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'xps_rxqs_map' not described in 'net_device'
../include/linux/netdevice.h:2100: warning: Function parameter or member 'qdisc_hash' not described in 'net_device'
../include/linux/netdevice.h:3552: WARNING: Inline emphasis start-string without end-string.
../include/linux/netdevice.h:3552: WARNING: Inline emphasis start-string without end-string.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: David S. Miller <davem@davemloft.net>