cve-update-nvd2-native: handle all configuration nodes, not just first

cve-update-nvd2-native: handle all configuration nodes, not just first

Some CVEs, such as CVE-2013-6629, list multiple configurations which are
vulnerable. The current JSON parser only considers the first
configuration.

Instead, consider every configuration. We don't yet handle the AND/OR
logical operators, but this is a step in the right direction.

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>