net/smc: Use active link of the connection

Use active link of the connection directly and not
via linkgroup array structure when obtaining link
data of the connection.

Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>