hw/usb/ccid: remove references to NSS

hw/usb/ccid: remove references to NSS

The NSS package was previously pre-requisite for building CCID related
features, however, this became obsolete when the libcacard library was
spun off to a separate project:

    commit 7b02f5447c64d1854468f758398c9f6fe9e5721f
    Author: Marc-André Lureau <marcandre.lureau@redhat.com>
    Date:   Sun Aug 30 11:48:40 2015 +0200

        libcacard: use the standalone project

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210623142245.307776-2-berrange@redhat.com>
Message-Id: <20210709143005.1554-10-alex.bennee@linaro.org>