powerpc: export of_get_ibm_chip_id function

Export the of_get_ibm_chip_id() function.  This will be used by the
PowerNV NX-842 driver.
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/powerpc/kernel/prom.c

@@ -800,6 +800,7 @@ int of_get_ibm_chip_id(struct device_node *np)
 	}
 	return -1;
 }
+EXPORT_SYMBOL(of_get_ibm_chip_id);
 
 /**
  * cpu_to_chip_id - Return the cpus chip-id