Fix an obvious 'is odd' check.

len % 1 is always true. Fix StrHexToBytes to do a proper odd length
check. This was only called by DevPathFromTextGenericPath,
ConvertFromTextVendor and DevPathFromTextMAC, which we've not had
a need to actually use just yet.

Submitted by: David Binderman
PR: 229718

lib/libefivar/uefi-dplib.h

@@ -576,7 +576,7 @@ StrHexToBytes(const char *str, size_t len, uint8_t *buf, size_t buflen)
 	/*
 	 * Sanity check preconditions.
 	 */
-	if (buflen != len / 2 || (len % 1) == 1)
+	if (buflen != len / 2 || (len % 2) == 1)
 		return 1;
 	for (i = 0; i < len; i += 2) {
 		if (!isxdigit(str[i]) || !isxdigit(str[i + 1]))