stmmac: fix driver built w/ w/o both pci and platf modules

The commit ba27ec66ffeb78cbf fixes the Kconfig of the
driver when built as module allowing to select/unselect
the PCI and Platform modules that are not anymore mutually
exclusive. This patch fixes and guarantees that the driver
builds on all the platforms w/ w/o PCI and when select/unselect
the two stmmac supports. In case of there are some problems
on both the configuration and the pci/pltf registration the
module_init will fail.

v2: set the CONFIG_STMMAC_PLATFORM enabled by default.
I've just noticed that this can actually help on
some configurations that don't enable any STMMAC
options by default (e.g. SPEAr).

v3: change printk level when do not register the driver.

Reported-by: Fengguang Wu <wfg@linux.intel.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 3638569..51b3b68 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -42,7 +42,6 @@
 #include <linux/dma-mapping.h>
 #include <linux/slab.h>
 #include <linux/prefetch.h>
-#include <linux/pci.h>
 #ifdef CONFIG_STMMAC_DEBUG_FS
 #include <linux/debugfs.h>
 #include <linux/seq_file.h>
@@ -2094,25 +2093,29 @@
 }
 #endif /* CONFIG_PM */
 
+/* Driver can be configured w/ and w/ both PCI and Platf drivers
+ * depending on the configuration selected.
+ */
 static int __init stmmac_init(void)
 {
-	int err = 0;
+	int err_plt = 0;
+	int err_pci = 0;
 
-	err = platform_driver_register(&stmmac_pltfr_driver);
+	err_plt = stmmac_register_platform();
+	err_pci = stmmac_register_pci();
 
-	if (!err) {
-		err = pci_register_driver(&stmmac_pci_driver);
-		if (err)
-			platform_driver_unregister(&stmmac_pltfr_driver);
+	if ((err_pci) && (err_plt)) {
+		pr_err("stmmac: driver registration failed\n");
+		return -EINVAL;
 	}
 
-	return err;
+	return 0;
 }
 
 static void __exit stmmac_exit(void)
 {
-	pci_unregister_driver(&stmmac_pci_driver);
-	platform_driver_unregister(&stmmac_pltfr_driver);
+	stmmac_unregister_platform();
+	stmmac_unregister_pci();
 }
 
 module_init(stmmac_init);