usb_device.h: Improve `LIBUSB_ERROR` macro

Guard macro parameters and correct a typo in the parameter name.

TEST=Build with `make distclean && make VERSION=none -j` with and
     without this patch, the flashrom executable does not change.

Change-Id: Ifc917b001713bc96adee46019d267f2090ef184a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/51114
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
diff --git a/usb_device.h b/usb_device.h
index b2c7656..4abf751 100644
--- a/usb_device.h
+++ b/usb_device.h
@@ -34,7 +34,7 @@
  * flashrom recognizes. It does so without displaying an error code allowing us
  * to compare error codes against the library enumeration values.
  */
-#define LIBUSB_ERROR(eror_code)		(0x20000 | -eror_code)
+#define LIBUSB_ERROR(error_code)	(0x20000 | -(error_code))
 
 /*
  * The LIBUSB macro converts a libusb failure code into an error code that