SPARC/LEON: avoid AMBAPP name duplicates in openprom fs when REG is missing

When the REG property is not available the NODE-ID is used as an unique
identifier in order to avoid filesystem name duplicates in /proc/openprom
filesystem

Signed-off-by: Daniel Hellstrom <daniel@gaisler.com>
Signed-off-by: David S. Miller <davem@davemloft.net>