octeontx2-af: Add mbox to alloc/free BPIDs

commit 3cdf79978ef9a4f38169ee982f6bba42aa91145c from
git@git.assembla.com:cavium/WindRiver.linux.git

Adds mbox handlers to allocate/free BPIDs from the free BPIDs pool.
This can be used by the PF/VF to request upto 8 BPIds.
Also add a mbox handler to configure NIXX_AF_RX_CHANX with multiple
Bpids.

Signed-off-by: Geetha sowjanya <gakula@marvell.com>
Change-Id: I7af084a5e87d68e87f5003c4a19ab943c884fb00
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/91350


Tested-by: sa_ip-sw-jenkins <sa_ip-sw-jenkins@marvell.com>
Reviewed-by: Nithin Kumar Dabilpuram <ndabilpuram@marvell.com>
Reviewed-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Wenlin Kang <wenlin.kang@windriver.com>