crypto: marvell: add synchronization between mailbox accesses

commit 15839ff7e4b74544a653a598394c1e6ca9f35774 from
git@git.assembla.com:cavium/WindRiver.linux.git

Since there are two workqueues implemented in CPTPF driver - one
for handling mailbox requests from VFs and another for handling FLR.
In both cases PF driver will forward the request to AF driver by
writing to mailbox memory. A race condition may arise if two
simultaneous requests are written to mailbox memory. Introducing
locking mechanism to maintain synchronization between multiple
mailbox accesses.

Change-Id: Icb3fc929e30e2f119d35f59582b53b7d9359d71b
Signed-off-by: Harman Kalra <hkalra@marvell.com>
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/70522
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Reviewed-by: Jerin Jacob Kollanukkaran <jerinj@marvell.com>
Tested-by: sa_ip-sw-jenkins <sa_ip-sw-jenkins@marvell.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>