amdkfd: Fixing topology bug in building sysfs nodes

Original code sent always 0 as the index number of the node. This patch fixes
this bug by sending a variable which is incremented per node.

Signed-off-by: Ben Goz <ben.goz@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>