hw/i2c/smbus_ich9: Fix the confusing contributions-after-2012 statement

hw/i2c/smbus_ich9: Fix the confusing contributions-after-2012 statement

The license information in this file is rather confusing. The text
declares LGPL first, but then says that contributions after Jan 2012
are licensed under the GPL instead. How should the average user who
just downloaded the release tarball know which part is now GPL and
which is LGPL? Also, as far as I can see, the file has been added to
QEMU *after* January in 2012, so the whole file should be GPL by
default instead.

Furthermore, looking at the text of the LGPL (see COPYING.LIB in the
top directory), the license clearly states in section "3." that one
should rather replace the license information in such a case instead.
Thus let's clean up the confusing statements and use the proper GPL
text only.

Message-Id: <1549471435-21887-1-git-send-email-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>