net: dcb: Fix kerneldoc warnings

net//dcb/dcbnl.c:1836: warning: Function parameter or member 'app' not described in 'dcb_getapp'
net//dcb/dcbnl.c:1836: warning: Function parameter or member 'dev' not described in 'dcb_getapp'
net//dcb/dcbnl.c:1858: warning: Function parameter or member 'dev' not described in 'dcb_setapp'
net//dcb/dcbnl.c:1858: warning: Function parameter or member 'new' not described in 'dcb_setapp'
net//dcb/dcbnl.c:1899: warning: Function parameter or member 'app' not described in 'dcb_ieee_getapp_mask'
net//dcb/dcbnl.c:1899: warning: Function parameter or member 'dev' not described in 'dcb_ieee_getapp_mask'
net//dcb/dcbnl.c:1922: warning: Function parameter or member 'dev' not described in 'dcb_ieee_setapp'
net//dcb/dcbnl.c:1922: warning: Function parameter or member 'new' not described in 'dcb_ieee_setapp'
net//dcb/dcbnl.c:1953: warning: Function parameter or member 'del' not described in 'dcb_ieee_delapp'
net//dcb/dcbnl.c:1953: warning: Function parameter or member 'dev' not described in 'dcb_ieee_delapp'
net//dcb/dcbnl.c:1986: warning: Function parameter or member 'dev' not described in 'dcb_ieee_getapp_prio_dscp_mask_map'
net//dcb/dcbnl.c:1986: warning: Function parameter or member 'p_map' not described in 'dcb_ieee_getapp_prio_dscp_mask_map'
net//dcb/dcbnl.c:2016: warning: Function parameter or member 'dev' not described in 'dcb_ieee_getapp_dscp_prio_mask_map'
net//dcb/dcbnl.c:2016: warning: Function parameter or member 'p_map' not described in 'dcb_ieee_getapp_dscp_prio_mask_map'
net//dcb/dcbnl.c:2045: warning: Function parameter or member 'dev' not described in 'dcb_ieee_getapp_default_prio_mask'

For some of these warnings, change to comments to plain comments,
since no attempt is being made to follow kerneldoc syntax.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20201028010913.930929-1-andrew@lunn.ch
Signed-off-by: Jakub Kicinski <kuba@kernel.org>