octeontx2-af: CN20K mbox implementation for AF's VF

octeontx2-af: CN20K mbox implementation for AF's VF

This patch implements the CN20k MBOX communication between AF and
AF's VFs. This implementation uses separate trigger interrupts
for request, response messages against using trigger message data in CN10K.

Signed-off-by: Sai Krishna <saikrishnag@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Link: https://patch.msgid.link/1749639716-13868-6-git-send-email-sbhatta@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>