net: hsr: fix debugfs path to support multiple interfaces

Fix the path of hsr debugfs root directory to use the net device
name so that it can work with multiple interfaces. While at it,
also fix some typos.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>