net: Move initialization of Au1x00 SoC ethernet MAC to cpu_eth_init

This patch will move au1x00_eth_initialize from net/eth.c to cpu_eth_init
as a part of ongoing eth_initialize cleanup work.  The function ret value
is also fixed as it should be negative on fail.

Signed-off-by: Shinya Kuribayashi <skuribay@ruby.dti.ne.jp>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/cpu/mips/cpu.c b/cpu/mips/cpu.c
index 38d8697..b7180b0 100644
--- a/cpu/mips/cpu.c
+++ b/cpu/mips/cpu.c
@@ -23,6 +23,7 @@
 
 #include <common.h>
 #include <command.h>
+#include <netdev.h>
 #include <asm/mipsregs.h>
 #include <asm/cacheops.h>
 #include <asm/reboot.h>
@@ -73,3 +74,11 @@
 	write_c0_index(index);
 	tlb_write_indexed();
 }
+
+int cpu_eth_init(bd_t *bis)
+{
+#ifdef CONFIG_SOC_AU1X00
+	au1x00_enet_initialize(bis);
+#endif
+	return 0;
+}