Refine detection for gpl-2.0-plus WITH mif-exception

### Description

We have a very specific bug with license detection for the mif-exception. The detection with SCTK v3.0.2 for lines 8-9 from the comments in jffs2.h was:
- gpl-2.0-plus 99
- mif-exception 99

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mtd-utils/include/jffs2.h - only file here
JFFS2 -- Journalling Flash File System, Version 2.

Copyright (C) 2001-2003 Red Hat, Inc.

Created by David Woodhouse

For licensing information, see the file 'LICENCE' in the
jffs2 directory.

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The relevant mif-exception text is:
As a special exception, you may use this file as part of a free software library without restriction. Specifically, if other files instantiate templates or use macros or inline functions from this file, or you compile this file and link it with other files to produce an executable, this file does not by itself cause the resulting executable to be covered by the GNU General Public License.

The relevant ecos-exception-2.0 text is:
As a special exception, if other files instantiate templates or use macros or inline functions from these files, or you compile these files and link them with other works to produce a work based on these files, these files do not by themselves cause the resulting work to be covered by the GNU General Public License.

The problem is that the the applicable exception should be ecos-exception-2.0 because the applicable license URL https://www.sourceware.org/jffs2/jffs2-licence.html does not mention "free software" which is restrictive coming from FSF.

Note also that the Notes from https://spdx.org/licenses/mif-exception.html: "Typically used with GPL-2.0 for older versions of GCC. This is similar to the eCos Exception." is misleading because the eCos Exception does not mention free software.