target/openrisc: Fix LGPL version number

target/openrisc: Fix LGPL version number

It's either "GNU *Library* General Public version 2" or "GNU Lesser
General Public version *2.1*", but there was no "version 2.0" of the
"Lesser" library. So assume that version 2.1 is meant here.

Cc: Stafford Horne <shorne@gmail.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
Acked-by: Stafford Horne <shorne@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1548252536-6242-3-git-send-email-thuth@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>