cxgb4: missing curly braces in t4_setup_debugfs()

There were missing curly braces so it means we call add_debugfs_mem()
unintentionally.

Fixes: 3ccc6cf7 ('cxgb4: Adds support for T6 adapter')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>