codestyle: Address issue related to R1702
codestyle: Address issue related to R1702

This patch addresses the following pylint issue R1702:

************* Module keylime.ca_util
keylime/ca_util.py:374:12: R1702: Too many nested blocks (6/5) (too-many-nested-blocks)

Signed-off-by: Stefan Berger <5c96973112e540fb909b13997fcd087e5bfbee96@linux.ibm.com>

mit-ll/python-keylime,mit-ll/python-keylime,mit-ll/python-keylime,mit-ll/python-keylime