BACKPORT: crypto: msm: Fix buffer overflow issue

In multi-threaded environment diglen variable could be modified
by multiple threads at the same time. Buffer overflow might
happen in current thread if another thread changes the diglen
variable. So add mutex locks to avoid this issue.

CRs-Fixed: 2010656
Git-repo: https://source.codeaurora.org/quic/la/kernel/msm-3.10


Git-commit: 70b719025fbef1fa98a2e3a823e583c836dd9bb2
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>
Signed-off-by: Dennis Cagle <d-cagle@codeaurora.org>

Bug: 37438302
Change-Id: Ib123d494ce6d258e82f77f8ac5eeeec30ff35b1b
Signed-off-by: John Dias <joaodias@google.com>