crypto: octeontx2 - prevent underflow in get_cores_bmap()

crypto: octeontx2 - prevent underflow in get_cores_bmap()

BugLink: https://bugs.launchpad.net/bugs/1959376
[ Upstream commit 10371b6212bb682f13247733d6b76b91b2b80f9a ]

If we're going to cap "eng_grp->g->engs_num" upper bounds then we should
cap the lower bounds as well.

Fixes: 43ac0b824f1c ("crypto: octeontx2 - load microcode and create engine groups")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>