[PATCH] app/test: add modexp group tests

[Akhil Goyal]

Hi Gowri,
> Subject: [PATCH] app/test: add modexp group tests
> 
> Add modexp tests for groups 5, 14, 15, 16, 17 and 18.
> 
> Signed-off-by: Gowrishankar Muthukrishnan <gmuthukrishn at marvell.com>
> ---
Can you rebase this patch so that CI can run?