crypto/mvsam: fix session data reset

crypto/mvsam: fix session data reset

This patch fix wrong clear memory session pointer.

When call mrvl_crypto_pmd_sym_session_clear function,
it might cause the following error:
CRYPTODEV: set_sym_session_private_data() line 497:
Set private data for driver 1 not allowed

This fix set zeroes to mrvl_crypto_session pointer instead to
rte_cryptodev_sym_session pointer, and will verify that
rte_cryptodev_sym_session pointer will not lose data such as
nb_drivers.

Bugzilla ID: 646
Fixes: 8a61c83af2fa ("crypto/mrvl: add mrvl crypto driver")
Cc: stable@dpdk.org
Signed-off-by: Dana Vardi <danat@marvell.com>
Reviewed-by: Michael Shamis <michaelsh@marvell.com>
Reviewed-by: Liron Himi <lironh@marvell.com>