[efi] Include a copy of the device path within struct efi_device

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/include/ipxe/efi/efi_driver.h

@@ -19,6 +19,8 @@ struct efi_device {
 	struct device dev;
 	/** EFI device handle */
 	EFI_HANDLE device;
+	/** EFI device path copy */
+	EFI_DEVICE_PATH_PROTOCOL *path;
 	/** Driver for this device */
 	struct efi_driver *driver;
 	/** Driver-private data */