hsr: avoid newline at end of message in NL_SET_ERR_MSG_MOD

clean follow coccicheck warning:
net//hsr/hsr_netlink.c:94:8-42: WARNING avoid newline at end of message
in NL_SET_ERR_MSG_MOD
net//hsr/hsr_netlink.c:87:30-57: WARNING avoid newline at end of message
in NL_SET_ERR_MSG_MOD
net//hsr/hsr_netlink.c:79:29-53: WARNING avoid newline at end of message
in NL_SET_ERR_MSG_MOD

Signed-off-by: Ye Bin <yebin10@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>