The valgrind checks for cert_create have not been run in a long while -
as such there are a few memory leaks present. This patch fixes a few of
the major ones reported by valgrind. However, a few do remain.

Change-Id: Iab002fb2b0090043287d43fb54a4d18928c2ed85
Signed-off-by: Justin Chadwell <justin.chadwell@arm.com>