Replace CONFIG_PPC_MULTIPLATFORM with CONFIG_PPC_PMAC in
drivers/net/tulip/de4x5.c.  It is needed for a pmac specific hook but
has nothing with to do with PPC_MULTIPLATFORM.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>