efi_loader: disk: a helper function to create efi_disk objects from udevice

Add efi_disk_probe() function.
This function creates an efi_disk object for a raw disk device (UCLASS_BLK)
and additional objects for related partitions (UCLASS_PARTITION).

So this function is expected to be called through driver model's "probe"
interface every time one raw disk device is detected and activated.
We assume that partition devices (UCLASS_PARTITION) have been created
when this function is invoked.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
index de2f34b..250eeb2 100644
--- a/lib/efi_loader/efi_setup.c
+++ b/lib/efi_loader/efi_setup.c
@@ -198,9 +198,7 @@
 	if (ret != EFI_SUCCESS)
 		goto out;
 
-#ifdef CONFIG_PARTITIONS
-	ret = efi_disk_register();
-#endif
+	ret = efi_disk_init();
 out:
 	return ret;
 }