stmmac: fix platform driver unregistering

This patch fixes platform device drivers unregistering and adds proper error
handing on module loading.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index 023a4fb..b05df89 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -127,14 +127,14 @@
 }
 static inline void stmmac_unregister_platform(void)
 {
-	platform_driver_register(&stmmac_pltfr_driver);
+	platform_driver_unregister(&stmmac_pltfr_driver);
 }
 #else
 static inline int stmmac_register_platform(void)
 {
 	pr_debug("stmmac: do not register the platf driver\n");
 
-	return -EINVAL;
+	return 0;
 }
 static inline void stmmac_unregister_platform(void)
 {
@@ -162,7 +162,7 @@
 {
 	pr_debug("stmmac: do not register the PCI driver\n");
 
-	return -EINVAL;
+	return 0;
 }
 static inline void stmmac_unregister_pci(void)
 {