common/octeontx: fix gcc 9.1 ABI break

common/octeontx: fix gcc 9.1 ABI break

GCC 9.1 fixes a bug with passing bitfields as pass by value in function
parameters and generates a warning for the same as below:

drivers/common/octeontx/octeontx_mbox.c:282:1: note: parameter passing
for argument of type ‘struct mbox_intf_ver’ changed in GCC 9.1

Fix the warning generated by passing bitfield as pass by reference.

Fixes: b4134b2d31cc ("common/octeontx: update mbox to version 1.1.3")
Cc: stable@dpdk.org
Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>
Acked-by: Harman Kalra <hkalra@marvell.com>
Tested-by: Ferruh Yigit <ferruh.yigit@intel.com>