ppc4xx: Change autonegotiation timeout from 4 to 5 seconds

I lately noticed, that newer 4xx board with GBit support sometimes don't
finish link autonegotiation in 4 seconds. Changing this timeout to 5
seconds seems fine here.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/cpu/ppc4xx/4xx_enet.c b/cpu/ppc4xx/4xx_enet.c
index 6ab04e7..697e038 100644
--- a/cpu/ppc4xx/4xx_enet.c
+++ b/cpu/ppc4xx/4xx_enet.c
@@ -106,7 +106,7 @@
 #endif
 
 #define EMAC_RESET_TIMEOUT 1000 /* 1000 ms reset timeout */
-#define PHY_AUTONEGOTIATE_TIMEOUT 4000	/* 4000 ms autonegotiate timeout */
+#define PHY_AUTONEGOTIATE_TIMEOUT 5000	/* 5000 ms autonegotiate timeout */
 
 /* Ethernet Transmit and Receive Buffers */
 /* AS.HARNOIS