crypto: testmgr - Validate output length in (de)compression tests

When self-testing (de)compression algorithms, make sure the actual size of
the (de)compressed output data matches the expected output size.
Otherwise, in case the actual output size would be smaller than the expected
output size, the subsequent buffer compare test would still succeed, and no
error would be reported.

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>